Are homosexuality/transexuality influence by genes or the environment?
[Two questions combined by cdg, 1 July 2004.]

-- Joanne (jo_4283@hotmail.com), June 30, 2004

Answers

There is research that supports both sides of this issue. The answer with these sorts of questions is almost inevitably "both." There is no simple answer. You'll just have to go and read the available resaearch literature.

-- Christopher Green (christo@yorku.ca), June 30, 2004.

Wrong question. You'll have to do further research on just how much each component might contribute. You might start by reading an article on transexuality in a current encyclopedia of psychology. You can do further reading on such topics in specialty journals also:

For example, the Journal of Homosexuality, at http://www.haworthpressinc.com/web/JH/

-- Hendrika Vande Kemp (hendrika@cox.net), June 30, 2004.

Hi Joanne, I concur with Hendrika, that both heredity (genetic influences)and the environment influence homosexuality and transsexuality. I would go on to say that most other physical and psychological traits, regardless of whether you consider the trait a normal variation or a disorder, are influenced by heredity and environment. It is typically a matter of trying to estimate the degree of hereditary versus environmental influence (e.g., using twin studies or family gene analysis)and trying to determine just how the various factors have their effects. It might be helpful to you to further divide the environment into prenatal and postnatal. This will allow you to emphasize that prenatal environmental factors can be particularly important in sexual development (as well as in the development of other systems). Prenatal hormone (e.g., testosterone)levels are considered particularly important in shaping internal and external genitals, sexual orientation, and some other sexual and nonsexual characteristics. These prenatal hormones levels are probably influenced by genes, but also by enviromonetal factors in the mother's environment, like severity or amount of psychological stressors (which can influence the development in the uterus). In addition to the known affect of psychological stressors on sexual orientation, other prenatal factors that could potentially influence various development systems are things like a mother's intake of illicit drugs, alcohol, smoking, medications (e.g., those that influence sex hormones), food deprivation, and prenatal exposure to viruses (e.g., flu virus). It is fascinating that some prenatal factors could influence a person's adult sexual orientation, but during prenatal development some systems go though a *sensative period*. Maybe you could think of some postnatal environmental factors that could influence sexual orientation. How about sexual orientation of family members, adolescent sexual experiences, or cultural tolerance toward sexual orientation? You may want to look at some twin concordance studies that look at sexual orientation. You also may want to deal with the issue of what is psychologically normal versus abnormal (which is a tough issue). I hope this helps. Paul

-- Paul Kleinginna (pkleinginna@georgiasouthern.edu), July 01, 2004.