How much of our children’s personality traits,
temperament, talents, health conditions, mental illness, and
intelligence are controlled by their genes and how much by the
environment we have created? What relevance does this have to us as
parents through adoption or donor egg or sperm? Our guests were:
• Dr. Matt McGue, Professor of Psychology at University of
Minnesota, a behavioral and quantitative geneticist, and
Co-Director of Minnesota Twin Family Study and the Sibling
Interaction and Behavior Study and Research on Adoption. He is also
an adoptive dad. • Dr. Nancy Segal, Professor of Psychology
and 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. • Dr. Jenae Neiderhiser, a professor of
psychology at Penn State University and Director of several long
term twin and adoption studies that look at the interplay between
genetics and environment.
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.
