What Twins Can Teach Us About Genetics vs. Environment
How much of our children’s basic temperament, their mental health, their intelligence, their learning disabilities, and all the things that make them who they are comes from their genes, and how much from their comes from their environment? What can we learn about genetics vs. environment from the ongoing twin studies, including the study of twins separated at birth? Host Dawn Davenport, Executive Director of Creating a Family, the national infertility & adoption education and support organization, interviewed three leading twin researchers: Dr. Matt McGue, Professor of Psychology at University of Minnesota, a behavioral and quantitative geneticist, Co-Director of Minnesota Twin Family Study and the Sibling Interaction and Behavior Study and Research on Adoption and adoptive dad; and Dr. Nancy Segal, Professor of Psychology, Director of the Twin Studies Center at California State University, Fullerton and author of Indivisible by Two: Lives of Extraordinary Twins and Entwined Lives: Twins and What They Tell Us About Human Behavior.
- There are different types of twin research designed to tease out the relative influences of genetics and environment.
- In general, the research shows an interesting mix between nature and nurture on how our kids “turn out”.
- Intelligence is impacted by both genes and environment. Adopted kids are usually more similar in academic achievement when living within the adopted family, but this environmental influence wanes as they age.
- Personality and temperament are highly influenced by genetics. Again, more so as the child ages. But there are some surprising areas or temperament or personality that are more influenced by the environment.
- Our guests evaluated the heritability of different types of mental illness, including bipolar, depression, schizophrenia, aggression, and alcoholism. We discussed the difference between being highly heritable and the odds of having the disease. We talked about this in the context of prospective adoptive parents evaluating an adoption referral or a potential birth mother match.
- We talked about epigenetics as it relates to donor egg, donor sperm or embryo donation (embryo adoption).
- ADHD and autism have a “moderate” genetic connection.
- Obesity is highly influenced by genes.
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Image credit: Donnie Ray Jones
Show originally aired in 2009.