1 MELLOW MUSIC What if we took a baby and watched everything that happened to it from birth to grave; if we examined every aspect of its life, looked at everything that happened to them and everything that made them who they are; their physical development, their personality ` their emotional ups and downs, criminal convictions, relationships, illnesses, highlights and heartbreaks? Then imagine if we did that for an entire city. Perhaps we could uncover what it is that really makes us who we are. That experiment has already begun. In 1972, the Dunedin Medical School embarked on the ultimate nature vs nurture test. They decided to take every child born in the city that year and follow them for life. For 40 years scientists have probed every nook and cranny of their existence. READS: A. Their medical history, their temperament, their genes, their private lives, successes, failures ` the lot. How many times have you sold hard drugs, like heroin, cocaine or LSD? The experiment is called the Dunedin Study and its subjects are now the thousand most-studied people in the world. And they've become the richest source of information on what really makes us who we are. You bash them first, then you get what you want. I'd stand them up, beat them up with the hammers, smash them with wood, kick them in. Left them lying in a pool of blood. Then you've got to think if they're going to ring the police afterwards, 'Should I kill this one or should I bash them beyond things so he can't talk?' Mm. Malcolm Cook has a long history of violent offending. He served time for a string of brutal crimes, including armed robbery and home invasion. Many people break the law but few are as violent as Malcolm. In fact, just 5% of men in any country will be responsible for 60% of violent crime. But why is Malcolm so different from the rest of society? Is it a choice or is there something that causes him to be this way? The Dunedin Study has answers, and it all boils down to the wrong combination. One way or another, violent crime affects all of us. The harm caused by antisocial behaviour impacts not just on the individual and those closest to them, but more widely. These are the people that all of us are concerned about. These are the ones that are intimidating, rob, steal or cause violence. And it's not just physical harm. Violent people cost society huge amounts of money in treating victims, police time and in the prison and justice systems. So antisocial behaviour is a problem in all ways. So what makes a small child grow up to be a violent criminal? Were they bad to begin with or is it their upbringing? Can any child end up like Malcolm? Professor Terrie Moffitt is the associate director of the Dunedin Longitudinal Study. She's spent decades studying violent offenders and how to deal with them. Most of what we do for young people who get involved in crime is we wait until they've been convicted on several different occasions, and in the end, we finally send them to prison, and by then they've committed already a lot of crimes and victimised a lot of people, and a lot of effort to, um, rehabilitate them at the point when they're already in prison has shown that that's not very effective. If rehabilitation and jail don't work, can we prevent children becoming violent or criminal in the first place? Having observed a thousand lives in detail, the Dunedin Study was in a perfect position to find out. They weren't the first to try. In 1775, Johann Lavater published Essays on Physiognomy. A wicked man walketh with a frown mouth. Lavater believed a man's moral character was written in his physical appearance. Continually he soweth discord. Building on this idea 200 years later, Sir Francis Galton devised a scheme to identify future criminals by creating composites of known offenders. The system failed miserably, but Galton's other idea using fingerprints to catch criminals was a huge success. By the time the 20th century rolled round, the issue had turned into an argument about nature vs nurture. Are violent criminals born that way or created in their upbringing? The Dunedin Study set out to find an answer. We were able to go back in the Dunedin Study and look at the data that had been collected and asked how early can you tell who's going to become involved in a life of crime. The study compared every member's childhood history with their behaviour as adults. Serious problems in relationships with friends? How many times do you carry a hidden weapon? An injury of some sort to a close family`? Or hurting someone to get them to have sex with you? The researchers spotted a trend. Almost all violent adults had something similar in their upbringing. What they really all have in common is a history of maltreatment or neglect before age 11. Abused children were much more likely to become violent criminals. However, it's not a definitive pattern. Many abused children still grow up to be perfectly normal members of society. They may be depressed and they may drink too much, but they tended not to get involved in violence. And some of them really are real successes. They own their own businesses, they have warm, loving relationships with their wives and children. So there had to be something else, perhaps something within them, and that pushed us to look for a gene. So the Dunedin Study decided to test subjects' genes. In 2003, the study set up the genetic laboratory here at Duke University in North Carolina. Genetic information was combined with the mountain of historical data already on file. These have been shipped all the way down from Dunedin on ice. Yep. They arrived frozen. Came about 24 hours overnight. However, humans have tens of thousands of genes. Researchers somehow had to decide in advance which genes to focus on. Help came when a Dutch woman walked into a police station with a life-threatening problem ` the men in her family. Many, including her son, were excessively violent and aggressive. One relative attempted to run his employer over with a car. Two were known arsonists. Another tried to rape his sister at knifepoint, and later stabbed a prison guard in the chest with a pitchfork. When she searched her family tree, she found it contained a long line of exceptionally violent men. Genetic tests revealed the men all lacked a common gene called MAOA. It was the kind of clue Dunedin researchers had been looking for. At this point we went back to our DNA tissue bank and tested for the MAOA gene among our study members. The missing MAOA gene in the Dutch men meant they were easily frustrated and extremely aggressive with little provocation, behaviour common in violent offenders. Some of us start off with collections from people who are not paying our bills. Open the door. Tried the normal way, you know. Talk, talk, talk, but it never works, so you just... you just punch them straight in the head and drag them inside and, basically, just take what they owe and more, whatever they've got. Could the MAOA gene be responsible for criminal violence? The Dunedin Study was about to find out. LAID-BACK MUSIC PLAYS THINKS: I blame the ocean. That's what divides us as people. 'I mean, if we drained all the sea from the planet, then we'd be connected.' THINKS: I have two PHDs. Should I go for a third? THINKS: 'I don't wanna throw the sea away. I mean, you gotta keep it; it's` it's of some use. 'Maybe up in space in a bowl.' THINKS: Bit greedy maybe. 'I'm just so smart.' LAID-BACK MUSIC CONTINUES PLAYING THINKS: 'Course, we'd have to house all the animals. CAR HORN BEEPS 'Ooh. 'Meanwhile, down on Earth, all those shipwrecks could become playgrounds for kids ` 'kids of all nations. (LAUGHS)' TYRES SCREECH LAID-BACK MUSIC CONTINUES PLAYING THINKS: Ow, my genius head. LAID-BACK MUSIC CONTINUES PLAYING 4 MAN SHOUTING IN BACKGROUND I've seen heaps of violence in jail ` gang beatings, pack attack beatings, stabbings, killings. If you want to study violence, then prisons are the perfect laboratory. There's just a million other people exactly the same as me. Then it just comes down to who's the biggest, who's the best. It's all run through threats and violence. So why are violent offenders like Malcolm so vicious and aggressive? The Dunedin Study wanted to find out. The first clue came from a violent family, all missing the same MAOA gene. The gene is found in everyone and it regulates hormones that affect mood and behaviour and our response to stress. We knew we had a candidate gene, MAOA, but we thought, 'How could a gene like MAOA 'possibly account for violence?' Violence is quite a rare thing, but MAOA alleles are very common. About one-third of people have the weak form. So we thought the gene alone cannot explain violent behaviour. At the same time the Dunedin Study was searching for the cause of violent offending in humans, the United States National Institute of Health was looking for the same thing in monkeys. They are really an excellent model for studying what we see in humans. Every day I'm amazed at how I will see so many behaviours that remind me of people that I know. (LAUGHS) Some are in my own family. And I'm not surprised at all because the genetic ladder between Rhesus monkeys and humans is very similar. They're about 95% similar genetically. Rhesus monkeys have exactly the same MAOA gene as humans, and as in humans, the gene comes in two forms ` a short, weak version and a long, high-activity version. Monkeys have something else in common with human society. There's a subgroup of monkeys in the wild, also 5% to 10% of the population, and they cause a lot of social chaos. And other monkeys don't like them. Children, we would call them bullies, and in monkeys we would call them jerks. Other monkeys don't want to play with them just like other children don't want to play with bullies. And more importantly, the intensity of the aggression escalates to the point where somebody could get hurt. The behaviour of these delinquent monkeys is strikingly similar to violent human offenders. The kind of situations that set them off usually involve some degree of frustration. They do stupid things that other monkeys know better than to try, like get between a high-ranking female and her kids, or they may repeatedly confront a dominant adult male, and when that male beats them back, they're right back in that male's face, and when that male beats them back again, they're right back in that male's face, so not surprisingly they illicit a lot of aggression from others. But in the wild, this kind of antisocial behaviour has a heavy cost. These exceedingly aggressive males, almost all of them get kicked out of the group well before puberty because the other monkeys in the group can't stand them, particularly the females, who consider them a threat to their kids, and most of them perish within a year. That is, most of them don't make it. The renegades represent the same 5% of the population that interested the Dunedin scientists. But so far, neither genes nor upbringing had explained why they were so violent. So the study took a different tack. It started looking for people who had both the MAOA gene and an abusive upbringing. And this time the analysis paid off. They found a link. If you looked at those guys who had the risk version of the gene and who were severely maltreated, fully 85% of them exhibited some form of antisocial behaviour by the time they were a grown-up. The genotype did not predict violence alone by itself at all, and maltreatment didn't predict violence alone by itself very well either. But when those two were found in combination, it could predict an outcome of violent crime really quite well. The Dunedin researchers had finally discovered a mechanism underpinning violent behaviour. It's as if nature loads a gun and nurture pulls the trigger. Malcolm Cook is not part of the study but his childhood was marred with appalling abuse and neglect. I got taken off my parents. I got taken off them at 23 months old. Malnutrition, ill treatment and living in squalid conditions and stuff, and, uh, alcohol and drugs, and, uh, yeah... I can remember one time I was chained up to a peach tree with a chain around my neck and padlocks, and my clothes stripped off, and kicked in with steel caps. Shortly after the Dunedin Study published its findings, the US National Institute of Health discovered exactly the same process in monkeys. If you look at the graphs coming from these two studies, they're tough to tell apart. That sort of thing is remarkable. Same genes, same pattern of findings, same relationship between differences in early social experiences with long-term consequences that you see even in adulthood. But what happens to someone with the problem gene who grows up in a good environment? Professor James Fallon is a neuroscientist at the University of California. He studies activity in parts of the brain affected by the MAOA gene. Early in the '90s, collaborators asked me to take a look at PET scans and SPECT scans of people who were in the penalty phase of murder trials. And when I found that I was able to really see which ones were the murderers, I became really really interested in this. Fallon's study of the criminal mind took an interesting turn when he decided to scan his own brain. It turns out my PET scan looked exactly like all the murderers that I had been looking at, that is the orbital cortex had turned off. The temple had turned off. Exactly the same pattern. So you can see in this particular person, both the cognitive and these more emotional areas of the brain are lit up. The same with this. This is a normal response. But if you look down here in the orbital cortex, this is somebody who is not using their emotions at all. There's just blue, so there's no activity. And this is a pathological sort of pattern. Well, it turns out that these are two people in my family of a number that are normal, and this is mine. That's the` That's, you know, a little bit disturbing. TV: ...Downtown Doll switches to the outside to challenge in second. Genetic tests reveal Fallon has the short or violent version of the MAOA gene. But Fallon's not a violent criminal. He's a successful university professor and family man. I got the joke cos I had been studying it and it really got me to thinking. I've got terrible genes, really, when it comes to behaviour, and also my brain pattern looks like somebody who should be impulsive and aggressive ` a violent person. So those two things together` If you'd just looked at two of them, you'd say, 'This guy is somebody who's in jail.' Research revealed another surprise for Fallon. There were seven convicted murderers in his father's family tree. OK. The party's over. So now this stuff really started to pile up and become quite personal. I had to eat some crow on this because I had always thought that genetics was very deterministic ` that 80% of who we are, we're just driven by our genes, and I had to back off on it. James, can you believe that he got this word? And, really, that third thing that's missing was that I was brought up so well, and there was no abuse. I had to not only thank my mother for the upbringing but, also, it meant to my colleagues that I was probably wrong. That I had really underestimated the role of environment in the interaction with genes. 30% of the population have the at-risk version of the MAOA gene, but the overwhelming majority are not violent people. If you look in any shopping mall, one-third of the people are carrying the low-activity MAOA genotype, and they're all just walking around doing their Christmas shopping and not really engaging in any violence at all. So it's a really special environmental circumstance that allows that genotype risk to be expressed in terms of criminal behaviour. 4 PEOPLE SCREAM WOMAN: Oh my God! 12.51pm, 22nd of February 2011, a massive earthquake devastates the city of Christchurch. In a matter of minutes, lives are turned upside down, people lose homes, businesses, jobs and loved ones. The catastrophe puts enormous stress on the entire community. Not everyone will deal equally well. Some people will be able to rebuild their lives, others will fail to cope. But why? And is it possible to predict who will permanently be affected and who will recover? We all experience life stress. It's part of being human, but why is it that some people experience this stuff and they succumb where others don't? Depression is a normal response to difficult circumstances. However, some people don't bounce back. They go on to develop a deep and lasting clinical depression. Almost one in five people will experience a serious episode of clinical depression in their lifetime. And the World Health Organisation believes it will become the number-one global disability within 10 years. This is different from just being a little down. It's very painful to the point of you being unable to do the things you normally do. You can't concentrate. You can't even get out of bed sometimes in the morning. There's just all the zest, all the passion, all the life force is drained from you, and people who have been clinically depressed, talk about it as one of the most aversive, unpleasant experiences they've ever been unfortunate enough to endure. And the cost is not just psychological. It's estimated depression is responsible for $19 billion a year in lost productivity in the United States alone. Is there serious illness, accident or diagnosis of a close family member? Yes. Dunedin researchers speculated that depression might be another gene by environment effect,... And was that an illness or an accident? Um, an illness. ...an effect triggered by overwhelming stress. But, again, they needed a gene to test. One candidate was a gene that had been the focus of a separate study involving MRI machines and pictures of human faces. We're going to run the faces task, and all you need to do is choose which one of the images on the bottom is identical to the image on the top. Dr Ahmad Hariri is interested in which parts of our brain light up when we look at photos of strong emotions. OK. Here we go. Our research at its core is really interested in understanding why people respond so differently to their worlds, and the why for us is at the level of the brain. How is it that each individual's brain is responding differently to the world and to the onslaught of information, the barrage of information and challenges that we face every day? The particular experiment that we conducted is designed to illicit a response in a very specific structure in the brain ` the amygdala. That's the central hub for learning about our experiences, especially fearful and stressful experiences. The subject is seeing these faces and the faces have different expressions. They learn that they mean something specific about their environment. They predict threat, for example. Like this is a classic surprised face here. Hariri found people with a certain gene had a strong physiological and brain response to fearful or threatening faces. The gene in question is called the 5-HTT serotonin transporter gene. Like the MAOA gene, it comes in a long and a short form. When the Dunedin Study looked for an interaction between the 5-HTT gene and stress, they found a pattern. The more stressful life events a study member had in the past five years, the more likely they were to develop an episode of depression if they had the short version of the serotonin transporter. Study members with the short version of the serotonin transporter gene were more likely to become clinically depressed or try to commit suicide, but only if they'd been mistreated as children or experienced adversity as adults. The people with the vulnerability version or the risk version of the gene in a world where there is plain sailing, would look no different from anyone else. However, with nasty stuff happening, stress, bad relationships, loss of a job, illness, chronic injury, they are more likely to become depressed and to think about or try to kill themselves. But what about people who have the good version of the gene? The non-vulnerable version, despite experiencing a lot of bad stuff, a lot of stress, don't seem to be any more susceptible or likely to develop depression. They seem to sail on through all the bad stuff, pretty much unscathed. Back in Virginia, the NIH found an identical interaction in monkeys. Animals with the short version raised in stressful environments developed common symptoms of depression. We found exactly the same things in our monkeys, both in terms of behavioural characteristics of depression, social withdrawal, lack of interest in social activity, lowering of activity levels, and these so-called depressed monkeys could be successfully treated with common human antidepressants, like Prozac. So far as arguing that these monkeys were depressed, that was a pretty good argument. So in terms of the Dunedin human findings, they were an exact match. Publication of the Dunedin results on depression was voted one of the most important scientific breakthroughs of the year, and the article continues to be one of the most referenced scientific papers ever published. It's no longer a matter of nature or nurture. Nature plants the seed and nurture is, of course, the watering and the sunshine. How the plant turns out depends upon not just what was in the seed to begin with, but what's in the environment surrounding it while it's growing. 5 The Dunedin study had proved our environment can actually change the way our genes operate. Genes don't necessarily have fixed outcomes. They can be activated or switched on by events in people's lives. Dunedin researchers suspected this might be a common mechanism in nature, and began looking for other genes that might be triggered by a person's lifestyle. This time we wanted to use an environmental circumstance that was not a social circumstance; not a stressful life event, not child maltreatment but something chemical. The chemical they focused on was cannabis, the most widely used illegal drug in the world. I'm a real nice person but I like fighting, so it's good to go to a special place where you can just train. I like painting. I like writing. Poetry is good. I'm a bit of a rapper. (LAUGHS) Chris McMurray is a typical 25-year-old, and like millions of others, Chris started experimenting with cannabis in his early teens. Probably get a tinny every few days between friends. Then it's about buying more, and, yeah, just quite a frequent user. And everyone else is having fun and you're having fun, and slowly small thoughts start becoming bigger. Mm. Chris was 17 when a night on cannabis and party pills took an unexpected and unpleasant turn. I'd been taking a lot of party pills, lots of weed, and stayed awake for four or five nights. And at the end, it just took me, and I was just like being swept by the wind. I was completely manic, just extremely, extremely high beyond anything I've ever felt before. And I was delusional. Thought I could read my friends' minds. Thought one of my best mates was trying to kill me. And then a white car went past and then a blue car, then a white car and a blue car, and a white car and a blue car. And it was the exact same cars repeating over themselves. And that was just spinning me out. Chris was diagnosed with drug-induced psychosis. It took me about three days to realise I was actually in hospital. Like, I'd been in the intensive care for a few days, and I looked up to the wall and it said 'mental health ward for youth'. And I was like to the person next to me, 'Am I in a mental health ward?' He's like, 'Yeah.' Unfortunately, Chris' symptoms didn't go away. Eight years on, he continues to suffer from schizophrenia. Typically, about one in a hundred people suffer from schizophrenia, however, 10% of study members who regularly used cannabis in their early teens, went on to develop the illness. This is 10 times the expected rate. Dunedin researchers suspected something else was interacting with the drug that made it particularly problematic for young users. You can imagine that people are very reluctant to believe that actually smoking cannabis can lead people to develop psychotic symptoms because there's lots of people using cannabis and lots of them don't develop psychosis. But an important element in that story are the genes. 80% of study members used cannabis before they were 26, and, of course, most hadn't developed schizophrenia. Clearly, marijuana use wasn't a cause by itself. So the study took a closer look at subjects' genes, and one gene in particular. The gene we chose to look at is called COMT. It was interesting because its effects in the brain are in the same brain systems where cannabis works and the same brain systems that are known to be abnormal in people who develop schizophrenia. So it was a good candidate gene to look at first. Um, and we found that the people with the risk genotype on that gene were more likely to develop psychosis in their 20s if they were heavy cannabis users before age 15. Once again, the Dunedin Study had found evidence that something outside us can modify the outcome of a gene, but this time it wasn't something social, it was chemical. So, again, the combination. The COMT gene was not related to schizophrenia unless you smoked cannabis, and cannabis was not related to schizophrenia unless you had the risky genotype. This gene environment-interaction finding, you know, is a great example of showing how the environment can amplify, you know, the genetic risk that some people carry around for developing mental-health problems later in life. Problems only occurred for those with the COMT gene who were using cannabis before the age of 18. People with the gene who started using cannabis as adults were not affected. Chris manages his condition with a mixture of antidepressants and cognitive therapy. I wish I really never took drugs. Wished I never smoked weed. I wish I never smoked as much as I did. Like, it's all catching up now. Yeah, it's difficult. The Dunedin Study members were teenagers in the mid-1980s. The potency of cannabis sold on the street has increased markedly since then and the number of teen users worldwide is growing. Today, surveys tell us that more and more and more young people are trying cannabis and that they believe that it doesn't have any negative consequences for them, so there may be more people affected by this situation today than there were in the Dunedin Study members. The Dunedin research revealed something else unexpected. Mental illness is not the only risk facing cannabis users. The study found that using cannabis can also affect our intelligence. Most people have been told that the IQ is perfectly stable and that once you're 15 years old, you never get any smarter or any thicker. Uh, turns out that's not quite true. There's quite a bit of change. Again, they discovered cannabis disrupted the growing brain. The study members who had a long-term history of persistent, regular cannabis abuse had lost intellectual functioning. They had lost IQ points. Now, as it turns out, it wasn't everybody who used cannabis that lost IQ points. The people who lost the most were those who started using the cannabis very early in life when they were, say, 13 to 15 years old. Users who were regularly smoking cannabis before they were 18 lost an average of eight IQ points, and that IQ loss appears to be permanent. Eight IQ points is the difference between a fish filleter and a fishing-boat owner. Uh, it's the difference between a dental hygienist and the dentist. So it does have a big association with the kind of work that people are able to master. Always better memory, better intellectual performance, stronger focus of attention helps you get further in education. Other studies back this up. Daily teen users are less likely to finish high school. They're also more likely to attempt suicide and to become dependent on cannabis. Young people need to be aware of the potential harm associated with using cannabis early in their life. I think there is, um, a wide belief that using cannabis is fine. It's like alcohol or it's like using cigarettes. Well, for your mental health, cannabis is not that, you know, easy-going. 4 The Dunedin study had discovered a mechanism that links at-risk genes to events in life that change the genes outcome for the worse. But it may not be that simple. These are not necessarily just bad genes causing depression or violent behaviour, they may also have a positive function. It is true that people, because of certain genetic make-up, are more susceptible to the negative effects of adversity. But fascinatingly and intriguingly, those same genes make people more likely to benefit from environmental support and enrichment. In other words, they are malleable on the upside too. And as a result, you're seeing genes, that look like they make people vulnerable, turn people into lucky people when things go well cos they benefit the most from it. So what at first looked like bad genes might actually be good genes for some people in the right circumstances. James Fallon thinks he might be one of those people. You can bet it, but we may not be able to watch it. If you looked at my genes, genetics would say that I would be a very aggressive person and probably somewhat antisocial. I have a lot of the characteristics that people have with these genetic combinations, but I'm not a criminal. You know, I haven't been in jail. I'm kind of a good boy, but I'm very aggressive and I hate to lose. I've just turned it into winning everything I possibly can. And what would Malcolm Cook's life look like if his childhood hadn't been shaped by neglect and abuse. It wasn't until he was in jail that he learned how to read. I used to go to court and I used to hear them read out big words and all that sort of thing. I knew nothing what they were talking about. And I started learning crosswords and that. Studying it real hard out, and I learned heaps of words, you know. And I thought, 'Ooh, is that what they're saying?' And all the time I was going, 'Yeah, I don't care. I don't care,' but if I had known what they were saying, I would have cared all right. Even a gene that appears to cause depression may have an upside in the right circumstances. The same amygdala, kind of excitability, that is associated with the shorter allele can be detrimental if you experience a lot of life stress, but if you have a nurturing life, if you have a lot of support through your friends and family, if you don't encounter a lot of negative stressors in your life, that same shorter allele and that same amygdala excitability can actually be very beneficial. Evidence that's emerging very recently suggests that you may be more empathetic towards individuals. You may be more responsive to the needs of others. In many ways, a more socially kind of responsible and proactive person. Even the so-called good version of the gene has a downside. The ones that we used to think of as resilient to adversity, well, they're also resilient to beneficial or supportive environments. It says to me, resilient people who don't succumb to adversity are actually just fixed or not malleable. They're not susceptible. They're who they are almost no matter what. Why would nature make some of us sensitive to what happens to us and others not? There is always a pro and a con. It's never one or the other. And this is something that we're beginning to feel, we're really starting to appreciate more and more, and we're reframing how we approach the study of common genetic variation. Having two versions of a gene available in a population means there will always be someone suited to the environment, regardless of circumstances. There is a large part of the population, the so-called dandelion kids, who are going to thrive in any environment, but then you have the orchid kids who are very sensitive to adverse environments and will wither away, but in a really good supportive environment, they absolutely flower and bloom and end up at the very top. You diversify your investments and you hedge your bets, and over time that pays off the best, so financial theory tells us. Well, Darwinian biological theory is more or less telling us the same thing. But what about people who, through no fault of their own, have ended up with the wrong genes in the wrong environment? They didn't choose their genes or their upbringing. Could defence lawyers argue clients were genetically predisposed to violent behaviour so they were less to blame? 'Your Honour, my client had the bad version of the gene and had a terrible upbringing. 'I know they did the awful, heinous crime, but please go easy on them 'cos, you know, they were predisposed.' It's no comfort to me to know that he couldn't help himself, right? I mean, that's the kind of person I'm most afraid of. You can envisage some juries thinking that, uh, the defendant couldn't help his act because he was genetically predisposed and therefore we should be lenient. Others would think, 'Well, if that's true, then he's more likely to reoffend in future 'and we should really give him a longer sentence to make sure that he can't get at the public.' So if I were a defendant, I would think it was very risky business trying to bring my genotype into the courtroom. The new knowledge about our genetic make-up raises potential problems for everyone. Could information about our underlying propensity for violence, depression or schizophrenia be used against us by the likes of insurance companies or employers? If you're an employer and you know that one person has the risk version or the vulnerability version of the serotonin gene, uh, and one person didn't, who are you going to choose to employ? What if certain ethnic groups have a higher percentage of these genes or not? We're really interested in that. Do we not want to know that? But fortunately, just knowing a person's genes is not enough. It's only half of the equation. The new model requires both genes and environment to create an outcome. Having a certain genotype is not destiny. It's a propensity, and that propensity is activated by features of the environment, and that's one of the most important lessons. Just having the genotype doesn't tell us very much. And that means that we can help turn on and off these genetic propensities by changing the context in which people grow up. The Dunedin findings have rewritten the nature versus nurture argument and revealed a mechanism that actively involves both. We can't change our genes but we can change the environment, and the earlier we act, the better. The best investment a society can make is to do things that allow mothers to be good mothers. I'd give them social support, give them stable things, protect them from raucous things going on as much as possible, and the group will benefit in the long range. The Dunedin researchers believe this nature via nurture mechanism is common. If this is the case, then everyone is likely to have some genes with possible negative outcomes. But the lesson is clear. No matter what genes we have, a positive upbringing will benefit anyone, and a safe and happy childhood is the best foundation for a happy life. Captions by Anne Langford. www.able.co.nz Captions were made possible with funding from NZ On Air.