Director & Researcher of the AIDS Epidemiology Group at the Department of Preventive and Social Medicine at the University of Otago Medical School in Dunedin
Not Clearly Pro or Con to the question "Is Sexual Orientation Determined at Birth?"
"These findings show that much same-sex attraction is not exclusive and is unstable in early adulthood, especially among women. The proportion of women reporting some same-sex attraction in New Zealand is high compared both to men, and to women in the UK and US.
These observations, along with the variation with education, are consistent with a large role for the social environment in the acknowledgement of same-sex attraction. The smaller group with major same-sex attraction, which changed less over time, and did not differ by education, is consistent with a basic biological dimension to sexual attraction.
Overall these findings argue against any single explanation for homosexual attraction."
"Same-Sex Attraction in a Birth Cohort: Prevalence and Persistence in Early Adulthood," Social Science & Medicine, Apr. 2003