From the ArcaMax Publishing, Health & Fitness Newsletter:
http://www.arcamax.com/news/healthtips/s-370740-685550
LONDON (UPI) -- A study of 3,826 same-gender twin pairs in Sweden
found homosexual behavior is largely shaped by genetics and random
environmental factors, researchers say.
Researchers at Queen Mary's School of Biological and Chemical Sciences
and Karolinska Institutet in Stockholm, Sweden, say that overall,
genetics accounted for around 35 percent of the differences between
men in homosexual behavior and other individual-specific environmental
factors accounted for around 64 percent.
Individual-specific environmental factors may include biological
processes such as different hormone exposure in the womb -- not
societal attitudes, family or parenting which are shared by twins, the
researchers say.
"This study puts cold water on any concerns that we are looking for a
single 'gay gene' or a single environmental variable which could be
used to 'select out' homosexuality," study co-author Dr. Qazi Rahman
of Queen Mary's School of Biological and Chemical Sciences said in a
statement
The researchers tracked all adult twins ages 20 to 47 in Sweden --
3,826 same-gender twin pairs, who were asked about opposite sex and
same sex partners.
For women, genetics explained roughly 18 percent of the variation in
same-sex behavior, non-shared environment roughly 64 percent and
shared factors, such as family environment, explained 16 percent, the
researchers say.
The study, published in Archives of Sexual Behavior, shows that
genetic influences are important but modest, and that non-shared
environmental factors, such as different hormone exposure in the womb,
dominate.