Is being gay hereditary

The Psychobiology of Sex Orientation 2nd ed. Vasey and VanderLaan tested the theory on the Pacific island of Samoa, where they studied women, straight men, and the fa'afafine, men who prefer other men as sexual partners and are accepted within the culture as a distinct third gender category. By way of analogy, the allele a particular version of a gene which causes sickle-cell anemia when two copies are present, also confers resistance to malaria with a lesser form of anemia when one copy is present this is called heterozygous advantage. Sexual orientation and science Biology of gender Behavioural genetics. However, this difference was not hypothesized a priori, was not large, and was the only group difference found out of many tested. Crime Education Leadership Social capital Suicide.

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Biology and sexual orientation

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The research consisted of 1, homosexual men and 1, heterosexual men. Since the hypothesis solves the problem of why homosexuality has not been selected out over thousands of years, despite it being antithetical to reproduction, many scientists consider it the best explanatory model for non-heterosexual behaviour such as homosexuality and bisexuality. Scholars have also pointed out that Darwin himself described kin selection in The Origin of Species , so under a Darwinian model of evolution, not only individuals, but family groups bloodlines can compete for selection. Another issue is the recent finding that even monozygotic twins can be different and there is a mechanism which might account for monozygotic twins being discordant for homosexuality. They argue that sexual orientation can shift over the course of a person's life. The researchers concluded that there was genetic material being passed down on the X chromosome which both promotes fertility in the mother and homosexuality in her male offspring. Retrieved June 12,

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While scientists do not know the exact cause of sexual orientation , they theorize that a combination of genetic, hormonal, and social factors determine it. The authors concluded that "our findings, taken in context with previous work, suggest that genetic variation in each of these regions contributes to development of the important psychological trait of male sexual orientation". A number of twin studies have attempted to compare the relative importance of genetics and environment in the determination of sexual orientation. According to Dean Hamer and Michael Bailey, genetic aspects are only one of the multiple causes of homosexuality. The concentrations of these chemicals is thought to be influenced by fetal and maternal immune systems, maternal consumption of certain drugs, maternal stress, and direct injection. The third group was of six women whom the researchers presumed to be heterosexual.

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