We are the Association for Child and Adolescent Mental Health, or ACAMH for short. And this is ACAMH learn. Hi, I'm Helen Fisher. I'm a Professor of Developmental Psychopathology at King's College London. And I have the real pleasure of currently leading the environmental risk longitudinal twin study. Hello, my name is Terrie Moffitt. I'm a Professor of Social Behaviour and Development at King's College London, at the Institute of Psychiatry. And together with Avshalom Caspi, who will speak next, I had the pleasure and honour of launching the E-Risk study about a quarter century ago. And I'm Avshalom Caspi. I'm a Professor of Personality Development at King's College London. I'll tell you about the original rationale for why we launched the E-Risk study. I remember that this was about a quarter of a century ago now. At that time, we knew in the field that anti-social behaviour was concentrated in families. We knew this because of research done at Cambridge University by David Farrington, who had reported that 10% of the families in Britain accounted for 60% of the crimes committed in Britain. At the same time, so we didn't really know why that was. Could it be because parenting was poor and therefore antisocial behaviour was transmitted socially within the family? Or could it be because there was a genetic risk for antisocial behaviour that was transmitted within the family? So this was also, remember at the heyday of parent training and parent education as new forms of intervention. So we're talking about in the 1990s. At the same time that there was an enormous enthusiasm for this ability to help parents raise their children properly, there was a surge in claims from academia that what parents do didn't matter. So there was a book called The Limits of Family Influence. There was a book that was very popular called Parents Matter Less Than You Think, and there was a book by Steven Pinker called the Blank Slate. So these books were causing people to think, oh, it's all genetics, whereas the intervention community was saying, oh, we can change it. So that was the conflict or tension around the time when we started the study. So what we did was, we noticed that the studies that were kitted out to answer this question were mainly twin studies. The problem with those twin studies was that they tended to be studies of well-off, well-educated volunteers, and they also tended to collect data in questionnaires and didn't actually go to the home and see the home environment and see how the child was growing up. So what they were reporting, those twin studies, was that it was pretty much all genetic. So we thought you needed a really fair test. You needed a test that really measured the worst parts of the child's environment. You need to measure things like child maltreatment, child abuse, domestic violence, parental discipline, parental monitoring, really go into the homes and observe. And you needed a sample that was representative of the population and included a lot of families that had severe disadvantage and a lot of really bad environments. So in order to give the environment a chance, a running chance, a fighting chance to show effects in a twin study, you needed a study like this. And that's how we designed the E-Risk study. There were several aspects of the study that we designed that were novel at the time, in the 1990s. There were four of those that I think are the most important. First one was, we sought to enrol twins of very high risk growing up in very high risk homes. So we enrolled twins who were born to mothers who had her first child when she was a teenager. So teenage mothers. And this gave us a near perfect match to the index of multiple deprivation in the UK. So the sample really does represent the most deprived families, and it also represents the most wealthy families. So the top 25% on wealth and the bottom 25% on poverty and deprivation are represented in this twin study, which was very novel at the time. The next thing was that, we wanted to actually measure the genes. So we got DNA. And this was in the 1990s. Not many studies were doing that yet. So at age 5, we took cheek swabs from the children, and we also took cheek swabs from their mothers. So it's one of the first studies to get both parent and child DNA for studies of genetics. And then the third thing was we conducted an actual home visit and sent research workers out to the home to stay for half a day. And there they could observe and record the family process and the family environment. They took video data. They took audio data in recordings. They conducted interviews with the parents, but they also conducted interviews with the children. So we used puppets in order to interview the children about their own conduct problems. So that was very, very novel. And then the last thing was that the design was to assess the children just before, and just after a major school transition, which would be causing stress on a family. So we collected data at age 5 and then again at age seven. So before and after school entry, then at age 10 and age 12, so before and after the move to secondary school. And then we were going to do age 16 and 18, but we didn't quite make age 16, but we did get data for age 18 when school leaving was occurring and stressing the child and the family. So those were the four novel parts of the design. This is a generally don't share secrets, but this is a secret I'm very happy to share with you. I think there are really two ingredients to the special sauce that accounted for the high retention. The first part of this special sauce, or secret sauce, was in-person assessments and home visits. The families really appreciated being visited and being made feel like they were really special, which they are. They knew that our team was travelling all over England and Wales just to visit them and just to listen to them. So we weren't taking an easy way out by mailing them or phoning them. We actually wanted to get to know them, and I think that did have a lasting impression. It's a memory that still has stayed with many of the children now that they're adults. The second part was that we really had the most amazing team of interviewers and examiners. These were people who just possessed this really unique blend of attributes. They were smart. They were flexible. They were warm. They were persistent. They were assertive. What a combination. And the moms loved speaking with them. The children loved playing with them as part of the examinations and the observations, and really, no one could resist them. The families always came first, and the interviewers were always willing to accommodate them and to meet whatever requirements or needs that they had. I think I also, it's important to pause here for a moment and reflect on why these participation rates and high retention rates are so important. Over the past 15 years, what we've seen in the social sciences are declining response rates to social surveys and a reduced willingness among people in the population to participate in research more generally. And all of this has also gone hand in hand with a greater mistrust of science in general. And I think the implications of what's happening really are profound. Reduced participation, especially among reduced engagement by lower-income and lower-education groups basically leads to results that misrepresent populations, and this misrepresentation affects our understanding of important social and psychological issues. And if our understanding turns out to be inaccurate, how are we supposed to affect policy recommendations? I think this is a big concern for the entire research community. We're currently interviewing the twins at age 30. And we're doing that slightly differently. So because of where we are now, I guess in the slightly post-pandemic world and the world of online that we have here, we wanted to provide the most flexible options for the twins, particularly at this point in their lives. So at 30, lots of them are giving birth. They've got little kids, or they're very busy at work and working long hours or doing all sorts of things. And so we wanted to give them ultimate flexibility and interview them in the online space. So we use online video interviewing to see them rather than go to their homes. And also because a lot of them are now living in lots of other parts of the world. So originally born in England and Wales, but a lot of them emigrated to Australia or Canada or France or other places. So this really gives us the option to see them at a time that works for them. So we're currently asking them about how they're navigating this kind of established adulthood period. So just in the early 30s now, just turned 30, and we're trying to get a sense of how are they reaching the kind of normative adult milestones we might expect at this point in time. How are they building their human capital for moving forwards with their lives into middle age? Getting a sense of what their family and their social relationships are like. And we're really keen to see also their adverse experiences. Have they experienced different forms of victimisation since we last saw them properly when they were 18? So whether that be in the online world or, most commonly, in the offline world, so domestic violence and other forms of victimisation that they could be experiencing in the adulthood phase. But we're also interested in how they've navigated that. Have they managed to find a way to grow from that, as well as the impact that might have had on their mental health? So we ask about a range of mental health difficulties. They might currently be experiencing, their use of substances, but also their physical health. How are they? How is their sleep? How are they experiencing chronic pain or a range of different physical health problems at this point? And then we also want to know what are they thinking about the future? What are their goals going forwards if they have any? Some of them may not have any plans at all. They might be living right now in the moment, but what are they worried about and what are they hopeful about for the future? So we're asking a lot of things in this online video world, but we also ask them to consent to give us a more biological samples. So we asked them if they'd be happy to give us a blood sample and also a buccal swab. And that will really give us some insight into what's happening on a biological level for them at this point. Are their genes being regulated in a slightly different way? What's happening in terms of their inflammatory markers and other kind of interesting aspects? Are they ageing biologically faster than some of the other twins? And we're also doing something quite novel and something that's becoming really important. And in the UK and across the world, which is asking them to consent to us the link to all the records that are held about them. So that's the kind of NHS, their medical records, their mental health records. So the way they've interacted with services, whether they've had different treatments as well as their education and their criminal records and their work and benefits and tax records and the wider environmental records held about them. So their exposure to air pollution, the energy consumption that they have, and what's happening in those wider communities that they live in. So that will allow us to really get a much bigger picture of their lives and how they're kind of reacting and living at this point in time. So we're excited to see what comes of that. And we'll be collecting that data just to the end of next year. So I'm hoping that's available for people to use in 2027. So I think I'll go first. On telling us about the favourite finding, my favourite finding, happens to also be the favourite finding of the mothers who took part in this study. And this is the study of twins who were separated when they entered school for the first time. So it was at that time the policy of many schools in Britain to separate twins and put them into different classrooms. The schools argued that the twins needed to build independence from each other and become their own person, and that they would learn better if they were treated like an ordinary child instead of a twin. Many of the mothers, however, felt that their twins were suffering emotionally from being separated. And so they ask us, the Twins and Multiple Births Association, TAMBA, ask us if we could please study that to give a science based answer that could inform the policy of the schools. So we were able to compare the identical twins, the monozygotic twins, to each other. Though what we were able to find was that those pairs of twins who were separated and put into different classrooms, if they were monozygotic identical twins, developed anxiety and depression as a result in their first year of school. The twins that were separated had more anxiety and depression than any monozygotic twins that were kept together in the same classroom. But what turned out to be really interesting was that the fraternal twins, the dizygotic twins. It didn't matter if they were separated or not. They did not develop anxiety and depression in their first year of school, depending on whether they were together or apart. So it really seemed to be something that was extra stressful for identical twins to be put into separate classrooms. So the mothers were proven right and their concerns were legitimate. And they were able to use that publication, which appeared in Twin research in 2004, to take it to schools and talk with them about their separation policy. So one of the findings that stands out in my mind, as I look back on many of the articles from the study, was an article that was led by Sarah Jaffe about the benefits of living with two biological parents. So many people believe that children need to have two married biological parents in the home in order to turn out well. And in fact, consistent with a lot of other research, what we showed was that, in fact, there were salutary effects that were associated with being raised by two biological parents. And specifically, the less time that fathers spent with their children, the more antisocial problems their children had. This is something that has been observed in many studies. But here comes the catch. The benefits of living with two biological parents actually depend on the father's level of antisocial behaviour. So, true, the less time that fathers lived with their children, the more antisocial problems their children had. But this was true only if the biological fathers were not antisocial themselves. In fact, when biological fathers were antisocial, the more time they lived with their children, the more antisocial problems their children had. So basically, what we found is that children who resided with antisocial fathers received a double whammy, kind of a double dose of both genetic and environmental risks for conduct problems. And the message of the paper is really that living with both biological parents, is not just the answer to the difficulties faced by some children in single-parent families, unless their father can also become reliable sources of emotional and economic support. And the finding was really interesting, I think in the policy world, where there have been so many debates about how to try to keep biological parents together. And so we were really engaged in with policy forms around this finding, and that was essentially, one of the goals of the E-Risk study set out to have. So when I was thinking about my favourite finding, it's hard because there are something like over 250 papers published on the E-Risk study over the years. So lots of things to choose from. But I wanted to pick one that really captured the essence of thinking about this longitudinal data that we have on the twins. So what is it about the early experiences that they have that could influence what happens to them as they move into adulthood? So over a decade or two decades of their life, what's actually going on? Are there really influences early that can affect them later in life? So this is a paper that was recently published in the Journal of Child Psychology and Psychiatry, and it's led by Alice Wickersham. And she looked at the question of whether the emotions that mothers express about their twins at age 10 is associated with those twins' own mental health as they transition into adulthood at age 18. So she looked at data from something called a five-minute speech sample. And so when the children were 10, the researchers that went into their homes asked them to talk about each of the twins separately, tell them what they were like, how they behaved, what went on. And from those very short speech samples, the researchers back in the office coded the levels of warmth and negativity. So criticism and potential hostile attitudes that the mothers had towards each of their twins. And then as we move through at 18, we assess the twins individually and privately, separate from their parents and the other twin, about their a range of mental health issues that they experience. So wanted to see is there a connection between those very early expressions of emotion from the mum and then what happened later. So what Alice found was that the children whose mothers were not particularly warm towards them, or had quite high negativity, so were quite critical and didn't particularly seem to their children when they described them at age 10, that those children tended to go on and have a range of mental health issues at age 18. But particularly tended to have higher levels of externalising behaviour symptoms. So they tended to have higher levels of things like attention deficit hyperactivity disorder. They tended to be more likely to be antisocial, to be dependent on substances at age 18. And that was even when we controlled for things like biological sex of the children, the socioeconomic status of the family, early emotional-behavioural problems the child might have had. But also when we looked at the identical twins compared to each other. So where they had the mother expressed slightly different levels of warmth and negativity towards them. If they had the twin that had the lower warmth and the higher negativity tended to have more behavioural issues later. And that's amazing, because what that does is it actually controls the way all of the genetic influences and all of the kind of unmeasured factors that are happening in that family environment earlier. So it gets us a little closer to inferring causality, not quite causality, but getting us a little closer on that journey to suggesting that the way the mum originally was, expressing her emotions about the child, and potentially then her relationship with that child early on, seems to potentially have an impact on the child's mental health as they move to adulthood. And that's important because it could really be used in the wider community, in schools, in nurseries, perhaps in GP practises, other areas to perhaps identify families where the emotions expressed by the parents towards the children are not ideal, perhaps low warmth and high negativity and identify families that could do with a bit of extra support. And perhaps interventions that could really help to prevent children from developing mental health problems later. So we need to do, obviously, more research on that. But it gives us a bit of a window into something that could really do important work in early prevention. Our immediate plans for the study are to finish seeing as many of the twins as we possibly can at age 30. So we're going to be doing that for about the next year. And then really try and capture as many of those voices as we can. We really want to get all of the possible twins we can. As Timmy said at the beginning, the study was set up to really capture the full kind of socioeconomic spectrum of families in the UK. So we really want to hear from the twins across all those different economic groups, and who have very different experiences. We want to make sure we are capturing the twins who've already had mental health issues, who have a criminal record or had lots of different types of experiences. We don't want to lose them. We want them to be part of the picture to make sure it is representative of young people's experiences. So we'll be busy doing that in the next year and coding the data and getting everything ready with the plan to really launch this data set in early 2027. Really to allow researchers from across the world to access this really unique resource, to answer a range of questions that are related to mental health, adversity and prosperity across the first three decades of life. And to capitalise on our twin design to really both understand what are the environmental influences controlling away genetic influences, but also what's the interplay between genes and environment in how those twins have developed as they moved across childhood, adolescence, and adulthood. So we'll be promoting that out and really keen to get people to use that. And people can look at our website to keep in touch with that and how they can access that data. And one of the other things we'll be doing is obviously wanting to analyse some of it ourselves and thinking about what we can do. And one of the things I'm really interested in, is thinking about the twins that we know have had a really difficult childhood. Either they've experienced maltreatment, or they've experienced quite severe poverty, or been exposed to domestic violence, or had quite severe mental health issues quite early. And I'm really interested to see, as they move into this period of established adulthood from 30 onwards, how have they managed to navigate that? Are some of them actually able to thrive and flourish and find their way through to get on with their lives and even perhaps enjoy them and establish their own families and move forward? So we'll be doing some research on that and trying to understand what's enabled them to get to that point with the idea that it'll hopefully inform interventions for people in the future. So we'll be doing hopefully some work on that. And then I guess looking even further forward, and we'll be obviously keen to see the twins again as they get older. And at this point, probably when they at least get to age 40, if not before, to see how they're progressing and navigating the next stage of their lives. So, yes, we look forward to seeing as many of them as possible and what happens to them as they move through the next few decades.