Adoption, Twins and the Genetics of Personality

Penn State undergraduate Alexis Capel interviews professor Jenae Neiderhiser about her long-term, interdisciplinary  research investigations into the interplay between genetic and environmental factors that shape the personalities of children as they grow into adolescence. By focusing on the development of adopted children and twins raised in different situations, Dr. Neiderhiser (an adopted person herself) is able to observe how these different factors play out. 

Alexis Capel
Undergraduate Biological Anthropology student at Penn State. 

Jenae Neiderhiser
Distinguished Professor of Psychology and Human Development and Family Studies at Penn State. 

Transcript

TT S2 E4 - Adoption, Twins and the Genetics of Personality

[THEME MUSIC]

 Mark Shriver: 

From Penn State’s Center for Human Evolution and Diversity, this is Tracking Traits

[MUSIC FADES]

Mark Shriver: 

Hello and welcome to the Tracking Traits podcast. My name is Mark Shriver and I’m the co-director of CHED, the Center for Human Evolution and Diversity at Penn State.

Nina Jablonski: 

And I’m Nina Jablonski, the other co-director of CHED. Welcome to the podcast.

Mark Shriver: 

Well Nina, we’ve got another great episode this month. 

Nina Jablonski: 

I know Mark! Why don’t you tell our listeners a little bit about it? 

Mark Shriver: 

Sure thing. This month we’re learning about the research of Jenae Neiderhiser, Distinguished Professor of Psychology and Human Development and Family Studies here at Penn State. She researches the way that genes and the environment work together to shape human development across the lifespan. In particular, this episode focuses on some really unique longitudinal studies that Janae has done on hundreds of sets of twins and adopted siblings over the course of many years. 

Nina Jablonski: 

Very interesting stuff! I think that we’re all naturally fascinated with the roles that genes play in our development, as well as environmental factors. And the way that Jenae has designed these studies is really ingenious. By incorporating siblings and twins that have grown up in different families, including adoptive families, she provides a lot of really rich insights into the this interplay of genetics and the environment.

Mark Shriver:

For sure. And to make things even more interesting, it turns out Jenae herself is an adopted person. 

Nina Jablonski:

That’s right. And as we’ve learned in past episodes of Tracking Traits, there is always a story behind the subject matter that researchers choose to pursue. And very often, there are very personal dimensions to those stories. 

Mark Shriver:

And what’s cool about this particular case is that Jenae opens up and shares some personal anecdotes about how this research helped her to get in touch with the way that  the genetics of her biological family set her apart from her adoptive family. 

Nina Jablonski:

So for Jenae, there’s an aspect of this research that is as much about personal discovery as it is about scientific discovery.

Mark Shriver:

That’s right Nina, in this case both of those things are going on simultaneously. 

Nina Jablonski:

That’s so cool.

Mark Shriver:

Absolutely.

Nina Jablonski:

And so, what about our interviewer?

Mark Shriver:

For this episode, Alexis Capel returns to the podcast to do the interview. She’s an undergraduate Anthropology student and listeners may remember her from our Season 2 opener with Eric Plutzer about the challenges of teaching science in the U.S. public school system. 

Nina Jablonski:

Alexis was great on that episode and did a fabulous job on this one too.

Mark Shriver:

That she did, Nina. Let’s give it a listen. 

Nina Jablonski:

Sounds good, Mark. Here’s Alexis Capel interviewing Jenae Neiderhiser about “Adoption, Twins and the Genetics of Personality.”

[MUSICAL INTERLUDE]

Alexis Capel:

Hello, Dr. Neiderhiser. It's lovely to speak with you today about your research. 

Janae Neiderhiser:

Thanks for inviting me. I'm happy to be here.

Alexis Capel:

Can you give the listeners and I a brief overview about yourself, your education and your work just to get us started?

Alexis Capel: 

Can you give the listeners and I a brief overview about yourself, your education and your work just to get us started?

Janae Neiderhiser:

Yes. I'm happy to. I am an adopted person and as an undergraduate, I was a psychology major and I had a biology minor. When I was looking at graduate schools, I knew I wanted to go to study child development and I saw that professor Robert Plomin in Human Development and Family Studies at Penn State was doing adoption research, looking at genetics and child development. So it was a very good fit. So I got my PhD in that program at Penn State and then for 13 years, I was in the department of psychiatry in George Washington University and returned to Penn State to the department of psychology in developmental.

Alexis Capel:

Your work is quite interdisciplinary, it sounds. To get a little more into the details of your work and how those fields that you mentioned influence it, can you describe to us how your research process is executed?

Janae Neiderhiser:

As I mentioned, I was trained in an interdisciplinary program, so human development and family studies when I was there at least included anthropologists, sociologists, psychologists, and some of the people in psychology were doing family research as well. And so I reach out to people in a variety of areas, depending on what particular study I'm attempting to pursue. And we put our heads together in such a way that everyone could use their knowledge in their particular field together and what we end up with is hopefully a much richer, final study that comes from a variety of different perspectives.

Alexis Capel:

Do you have a favorite part about your research?

Janae Neiderhiser:

What do I like most about my research? That's an interesting question and you'll probably get a different answer on a different day, but most of the time, I think what I like most about my research is developing the ideas and the research studies. A lot of people who do research, talk about grant writing with a groan and I agree, grant writing is hard. But it's also a lot of fun because you get to learn about a new area usually, and you talk about all these really exciting things you're going to do and that in my mind is one of the best parts of research and doing the studies as well is a lot of fun. But coming up with the ideas , working with my colleagues and my collaborators and their different disciplines, thinking about how best we can do the kind of work we want to do, answer the kind of questions we want to answer. That is definitely one of my favorite parts.

Alexis Capel:

On the other hand, are there challenges that you face?

Janae Neiderhiser:

There are always challenges because the work I do requires a lot of specialized populations. So for example, I am doing an adoption study now, and to do this study, we recruited adoptive parents and birth parents who had recently completed adoption plans. We started recruiting people three months after the placement, and most of the children were placed pretty much at birth. So to do that, we had to work with adoption agencies, and this was a collaborative project like everything I do. A t the time I was at George Washington university. So there was a DC site and there was a California site and there was an Oregon site. And we thought, oh, we'll work with agencies that are just two hours away from each of those sites. But people move, families move. Our families are all over the country and also live internationally.

Janae Neiderhiser:  

And it is a lot of work. It was a lot of work to recruit the sample and it's been a lot of work to keep in contact with them and to follow them and we've now been following them for over 15 years. Children have grown up in this study. And some of them are done with this study, partly because they've worked with this study so long, but the data we are collecting is really, really rich. But it's also very challenging to try to recruit such specialized samples and to try to maintain the samples over time. Especially when they're spread out all over the country, and COVID has of course made that even more difficult. 

Alexis Capel:

The studies you do are longitudinal or happen over a long period of time, which is basically from when the child is born or very young up until they're about 18, correct?

Janae Neiderhiser:

Well, that's what that study is doing. Yes.

Alexis Capel:

Do parents have positive or negative reactions? Do they end up pulling their kids out of the study? Do they have good positive feedback?

Janae Neiderhiser:

It really depends. Some families are really , really invested in the study and like being part of it. They've made friends with some of the interviewers. Maybe they've had the same interviewer come to their house multiple times because we have some long term interviewers who've been part of the study really since the beginning. And we have other families who are really difficult to reach and you know, it might take several months until you can actually get a human being on the phone and schedule and assessment. So it varies. It also varies in part, depending on what the study is about. So most of the time our studies are about the parent child relationships, what the child's behavior is like, their temperament and now that they're older, things about their peers and their academic achievement. But we are also part of a large NIH initiative and it is requiring a lot of very medically related things that we haven't typically asked our families to do and as a result, some of our families are not liking that study quite as much as they have liked other versions.

Alexis Capel:

Adoption studies, what's unique about them?

Janae Neiderhiser:

Adoption studies are really interesting because if you follow the birth parents and the adopted to child and the adoptive families, you're able to by design, separate genetic prenatal environment and rearing environmental effects, if the child is placed at birth or near birth. And the birth parents provide their genes and they're not parenting the child and in the case of the birth mother, they also of course provide the prenatal environment. So you're able to distinguish those. 

Janae Neiderhiser:

In our study, what we've done recently is we've also included a sample of siblings who are being parented by the birth parent. And that is very messy, but also very   because many adoption studies have comparison samples of biological parents rearing a biological child, but usually those biological parents are matched to the adoptive households to try to control on the environment. And in our study, we are very loosely controlling on the genetics because it is the birth parent of one of the children in our study who is parenting the child. And I say very loosely control on genetics because most of the time these children are going to be half siblings. So unless we had a very large sample of identical twins who were separated at birth, which doesn't happen very often, we can't really control on genetics.

Alexis Capel:

How has your journey as an adopted person influenced your research?

Janae Neiderhiser:

Well, as I mentioned at the beginning, I did become interested at least in part in this work because I am adopted and I thought it was very interesting to study adopted people. And it also had a genetics component, which I had found very interesting as an undergraduate. I was interested in genetics, partly because all my life, I knew I was adopted. I've always known I was adopted. I'm sure there was a time when I didn't know it, but I can't remember it. And I looked a little bit like, I guess I still do like my adoptive mother. She passed away when I was 13 but having said that I was always told in high school and that I was not like the other Neiderhiser kids in our town and there were many Neiderhiser's in my town because I did very well in school and things like that.

Janae Neiderhiser:

So I became curious about understanding how that was. And I thought about it as probably being something genetic. And when I was in my 20', I met my birth mother and I found out that one of her brothers, she had I think four brothers, I can't remember right now, but one of her brothers is a marine biologist PhD. And another of her brothers he started some big company or something like that. And I was like, "Oh, okay." And I found out my birth father was in law school at the time that I was conceived and the personal bit about that is when I met my birth mother, I looked at her and I have blonde hair and blue eyes and she has brown hair and brown eyes. And I also met my birth grandmother who also has brown hair and brown eyes but when she smiled, my birth mother and my birth grandmother, when they smiled, it was my smile on their face.

Janae Neiderhiser:

And I had never in my life seen that before, which is really interesting because like I said, I did resemble my adoptive mom. But when you grow up with something like that, where your family members make expressions that look like your expressions, you don't notice it. But when you've never seen that before, it is really very noteworthy.

Alexis Capel:

That's amazing. I know for myself, with my biological parents, I am very much interested in seeing what's the same and what's different about myself. And if I could see myself in my parents or vice versa. So I'm always pointing out those tiny little details. Oh, I have your nose or, oh, you have my smile or something like that. So that's super interesting.

Janae Neiderhiser:

Yeah.

Alexis Capel:

Thanks for sharing that.

[MUSICAL INTERLUDE]

Alexis Capel:

You mentioned how COVID has affected your research. Can you explain a little bit more about that?

Janae Neiderhiser:

In March, 2020, we were in the process of interviewing families, and what that entails is our interviewers drive or fly to the families’ homes, go into their homes, spend two to three hours at least collecting data. Some of the data they collect is videotaped interactions. And some of the data are questionnaire, computer-based interviews, things like that. So when it became clear that that was probably not something safe to do, that we didn't want to be sending our interviewers on airplanes for one; and that participants were not going to be welcoming anybody into their home until they figured out what was happening, we immediately switched to all-remote assessment. 

Janae Neiderhiser:

And it actually worked out pretty well, especially in the beginning I think everybody was very confused about what was happening. A lot of people were stuck at home. Schools were closed. Work was closed in a lot of places. So we had a lot of people really excited about participating in our study. We came up with an innovative strategy that a lot of other studies are also using. Probably a lot of people came up with this strategy at the same time, which is purchasing an iPad, sending it to the family preloaded with our app, because we have an app through which we collect the data and that's actually worked out pretty well because some people may have limited internet access. So we purchase a cellular plan that stays on the iPad for a month so they can use it for our assessment and they get a month of internet usage. It's always better to see people in person to some extent, but this is working out okay.

Alexis Capel:

So your work deals a lot with gene/environment interactions. Could you explain how our genes are shaped by the environment around us during early adulthood and adolescence?

Janae Neiderhiser:

Sure. So there are two different types of gene environment interplay that I tend to look at. The thing I look at most is gene/environment correlation and it's really how one's genes are correlated with their environment. And there are a couple of different ways this can happen. What I'm most interested in is how children (and adults for that matter) shape the environments that they are in, and in particular relationships with other people. So in other words, children can evoke a response from their parents and they can do that because of their temperament,  because of a variety of things and some of that will be explained by the child's genes. So in other words, if two identical twins evoke a similar type of parenting as compared to two fraternal twins who share half as many genes, that would suggest that the parents are parenting to something about the twins that's genetically influenced.

Janae Neiderhiser:

In the adoption study, what we can look at is if adoptive parents are parenting the child in a particular way, and that is related to the birth parent. The only way that makes sense is if there's something influencing the child through the genes they share with their birth parent that's then evoking a response from their adoptive parents, which is I think very fascinating, and it helps to show that children are not passively receiving the environment that they experience they're also influencing it. And people who have more than one child would say, of course they are. But the research to date wouldn't necessarily indicate that we understand that, because so many studies are just looking at a single child very often with their mother. And gene/environment interaction is another thing that we do look at and, The effects of the environment are changed as a function of genotype or vice versa, right?

Janae Neiderhiser: 

An example would be a child who has a birth mother who has been diagnosed with major depression. And that child is reared in adoptive household, where for whatever reason, harsher levels of discipline are applied. The environment can work together with the child's vulnerability that they from their birth parent to put the child at higher risk for developing depressive problems or related other problems. So that's an example of a gene environment interaction.

Alexis Capel:

So it kind of sounds as though the nature versus nurture conversation comes into play. 

Janae Neiderhiser:

I would say that it's more like nature with nurture, because it's not either/or. It's both. And it's understanding how they're working together that I think is, well, most interesting to me, but also most relevant and closest to the way that things are actually working.

Alexis Capel:

Does this broadly relate to the field of epigenetics?

Janae Neiderhiser:

In a general way since epigenetics is looking at how the environment can explain or cause genetic changes that's consistent again in a general way to what we do. So we do look at how the environment can change genetic risk or genetically influence characteristics in children.

Alexis Capel:

Do hormones happen to play a role in this gene environment interplay? 

Janae Neiderhiser:

We are looking at how hormones may also play a role. In this same adoption study, we're looking at how genetic factors, prenatal environment, rearing environment, and puberty hormones may work together to influence a child's adolescent development.

Alexis Capel:

The work you do is very important in understanding ourselves and how we have been shaped by not only our genetics, but those around us when we're growing up, which leads me to my next question. What impacts does your research have on your field and society?

Janae Neiderhiser:

Good question. Sometimes I think my research has no effect on my field, but on better days, I would say that I think that the one thing that the work I've done has done for my field is to help developmental researchers and others, family researchers, prevention researchers, think about how genetics may help to improve their understanding of the effects they're seeing. So for example, a lot of studies that look at how parenting affects child outcomes should also think about, well, the parents and the children also share genes. So if you measure things about the parent that you're also measuring in the child, you may get a little bit of a handle on that and really understand how parenting, the independent role of parenting. I mean, that's going to be confounded in a study of biological parents rearing their biological child, but it's better than not having anything at all in that regard.

Janae Neiderhiser:

And I think that in regard to prevention science, one thing prevention scientists have been doing is thinking about genetics as a way to explain why prevention doesn't work for all children, right? So that's another nice thing. Some children are simply going to respond better to a particular intervention for whatever reason, and some of that reason will be their own genetic makeup.

Alexis Capel:

What would you say is most important in your work to the framework of diversity?

Janae Neiderhiser:

Yeah, our field has not been very good in regard to diversity, but it needs to be better. And there've actually been a lot of really interesting papers published recently on how absolutely critical it is. What I can say is that most of the work I do is family-based genetic research. So twin or adoption studies. And the vast majority of that work has been done on white samples of Western European descent. That's changing. It's changing slowly. Part of the reason it's changing slowly is that there is a completely understandable distrust of genetic research in some communities that we would like to be reaching better. But having said that, a lot of people in the field, in my field, but of course also in other fields are talking about ways to better reach diverse communities so that we can include more diverse communities in our samples and about the absolute essential need for including more diversity in genetic research.

Janae Neiderhiser:

And just one thing worth mentioning is medical research, for example, which is talking about currently uses some genetic information to inform treatment options and almost all of that research has been done on white participants. So it's hard to know how, and if it applies to other populations, if you're not even including them in the study. So it's it something we all need to do better and I think many people are trying to do it better.

Alexis Capel:

I think many could benefit from that as well.

Janae Neiderhiser:

Yeah.

Alexis Capel:

Being a part of Penn State allows you to have access to many outlets and opportunities. How has Penn State become important to your research?

Janae Neiderhiser:

Penn State is great place to do the kind of research I do. I am a co-fund with the Social Science Research Institute, which deliberately creates collaborations or they do these group hires where they're hiring people in a variety of different departments who do similar types of research. So I was hired in psychology. Somebody was hired in anthropology and another person was hired in human development and family studies. And that creates an instant, small community of people in a variety of areas who can and often do collaborate. And hopefully as a result, all of the science is a bit richer, but even if I hadn't come as a co-fund, as we are called, I still would find this environment to be very rich because what Penn State does really, really well is collaborative research and interdisciplinary work.

Janae Neiderhiser:

And Penn state is really I think, unique in encouraging that kind of work and in supporting that kind of work in a variety of different ways. Many universities don't have that philosophy and it is a tool that we use, well and honestly, in recruiting new faculty to come to Penn State. And it is not something that happens everywhere.

Alexis Capel:

I'm sure you have tons of advice, but what is one piece of advice that you would give to younger, aspiring scientists that may be listening?

Janae Neiderhiser:

I don't know if I have tons of advice. One thing I think I would say to a young aspiring scientist is to pursue what you find to be exciting because the work is hard and you need to really be excited by it and to find it interesting enough to be worth the hard work that you'll need to put in. And that isn't to say that it will always be fun. It's not always fun. But if you…if you're working hard and you are really enjoying what you do, there's nothing better.

Alexis Capel:

I'm also very curious to know, what's next for you?

Janae Neiderhiser:

One thing that I'm doing right now is working with, a recently hired person in my department, Rina Eiden and a person in kinesiology (again, cross-disciplinary always), Danielle Downs. What we are doing is recruiting a cohort, a birth cohort of women living throughout the state of PA with an emphasis on a more rural population with the idea of following women from early in their pregnancy and following the children to get a sense of some of the unique needs and characteristics of a rural population. The majority of research period is done more in suburban and urban environments and Pennsylvania has such a large percentage of the population who are not living in those suburban or urban settings. Reaching them and understanding their needs and also trying to take advantage of what we've been learning about remote assessment to allow those populations to be reached in research, but also with healthcare, we have some collaborators at Hershey and at Geisinger that would, I think, add quite a lot to our understanding of development.

Alexis Capel:

Thank you so much again, Dr. Neiderhiser for taking the time to speak with us about your research. It has been an honor and a pleasure.

Janae Neiderhiser:

Thank you. Thank you very much, Alexis, it's been great.

[MUSICAL INTERLUDE]

Mark Shriver:

Tracking Traits is a production of Penn State’s Center for Human Evolution and Diversity. Our producer, audio engineer and musical theme composer is Cole Hons, and our logo was designed by Michael Tribone of mtribone design. 

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You can also follow us on social media and learn more about CHED and all of our interviewers and guests at our website, ched – that’s C H E D, dot L A dot P S U dot E D U.