I have long been fascinated by the age-old debate about nature vs. nurture. One of the most fascinating contributions to this debate is the ongoing longitudintal twin studies in the US. In the Creating a Family radio show aired this week I interview the directors of two of these studies. Wow, is all I can say!
We talked about all things twins: identical (monozygotic) twins, non-identical (dizygotic) twins, virtual twins (non related children of the same age being raised in the same family), and similarities and difference between adopted siblings. We discusssed what traits, medical issues, mental illnesses, developmental delays, etc. are heritable and which are controlled by our environment.
What We’ve Learned about Nature vs. Nurture
Twin studies are designed in different ways, but the one I find most illuminating (and sad) are the studies of twins separated at birth and reared apart. Dr. Nancy Segal, Professor of Psychology, Director of the Twin Studies Center at California State University, Fullerton said that from these studies they have learned that basically everything that they can measure in the psychological and behavioral domains has some degree of genetic influence. Dr. Segal spoke of some of the uncanny mannerisms that psychologist and geneticist had not thought to have a genetic influence.
Twins Separated by Adoption
In years past most of the twins separated at birth were separated by adoption. In part because it was easier to find families for one baby rather than two, and in part, at least in one now infamous case, because it was believed that separation made it easier for twins to develop separate and stronger psychological identities.
We talked on the show about Louise Wise Services, an adoption agency in New York City. In the 1960s and 1970, psychologists Viola Bernard and Peter Neubauer persuaded the agency to separate twins that became available for adoption. They did not tell the adoptive parents that their children were twins, but they did tell them that the children were part of an ongoing study of child development and asked then to continue to participate.
The study ended in 1980.
Realizing that public opinion would likely question the ethics of the study, the lead researcher, Peter Neubauer, decided against publication. The results of the study have been sealed until 2066 and given to an archive at Yale University.
Twins Continuing to be Separated
I asked Dr. Segal if she was able to find current participants for studies of twins separated at birth since fortunately adoption agencies now make all attempts to keep siblings and especially twins together. The primary reasons twins are now being separated is:
Chinese adoptions. With the one child policy sometimes a family in China would keep one child while abandon the other at an orphanage. Sometime both babies were abandoned at different times and different locations so that orphanage workers did not know that they were twins. Sometimes orphanages did realize the infants were twins, but thought it would be easier to find homes if they were placed separately.
Assisted Reproductive Technology. More twins are being conceived via IVF. Some parents do not feel equipped to raise two children, so they keep one and place the other for adoption. (This reason surprised me since I have not heard of this happening much, and I don’t know the frequency of occurrence.)
Single mothers with limited financial resources. Sometimes a woman when faced with the realities of raising twins decides to raise one and place the other for adoption.
Switched at hospital/Hospital mistakes. According to Dr. Segal, switched at birth stories are still happening. When one of the infants switched is part of a twin group, the result is separated twins.
I think you’re going to enjoy this show as much as I did. Thoughts? Would you adopt twins if given the chance? If you conceived twins unexpectedly through IVF, and did not feel able to raise both, would you ever consider placing one for adoption?
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I was too an identical twin. Back when I was born in April 21st 1983 . My identical twin sister was I guess adopted and my parents decided to keep me and raise me. When I turned 16 my mom had set me down and told me I had a twin sister but she said she didn’t know what had happened to her after we were born . And it wasn’t until last year my dream had came true when moving to Lexington and that was the most happiest emotional moments of my life when I had finally got to meet her in person. We’re sorta like identical mirror twins . Cause we walk , talk , dress and act exactly alike. But the only difference between us is she stays in trouble all the time and I’m the exact opposite I stay out and away from trouble and try to avoid it. But the best part about it is we love to switch places with one another just to mess with people and get them confused
I know two kids that are freshmans in high school. They are twins. I have an identical twin brother myself. The only difference is that my brother and I were not adopted. By my good friends that are twins were adopted early. The fact that many twins don’t end up with the same family is upsetting. Twins should be born Together and know each other. I have to show them this page, to show them how lucky they are to be with each other even after adoption!
I am so interested in this topic and I want to write a research paper for my Psych class. Is your biology your destiny? Something like that. Anyway, I would be interested in any other research you would have on the topic!
Yes, it’s a fascinating topic. We have a couple resources that you might find helpful for learning more, found by searching “nature nurture” – there’s plenty more, too:
Good luck and thanks for reading!