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group_3_presentation_3_-_biological_basis_of_sexuality [2018/03/30 23:44] rettag [Chromosomes Xq28 and 8] |
group_3_presentation_3_-_biological_basis_of_sexuality [2018/03/30 23:53] rettag [Man-Loving Genes Hypothesis] |
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| ====== Genes and Sexuality ====== | ====== Genes and Sexuality ====== | ||
| - | There has been extensive research done to determine if there are genes that lead to different phenotypic traits of sexuality. Most studies have focused on homosexuality in males, mainly because sexuality in females is typically more fluid, and thus males are easier to research. There are two main hypotheses that look into genes for homosexuality in males. | + | There has been extensive research done to determine if there are genes that lead to different phenotypic traits of sexuality. Most studies have focused on homosexuality in males, mainly because sexuality in females is typically more fluid, and thus males are easier to research. In addition, many researchers have concluded that male homosexuality is genetic and likely passed on from the maternal chromosomes. These conclusions have led to the following two main hypotheses that look into genes for homosexuality in males. |
| ==== Man-Loving Genes Hypothesis ==== | ==== Man-Loving Genes Hypothesis ==== | ||
| - | This hypothesis was first thought of by an Italian researcher named Andrea Camperio-Ciani. He and his colleagues found that there is "evidence for maternally inherited factors favouring male homosexuality and promoting female fecundity" (Camperio-Ciani, Corna, & Capiluppi, 2004). This "Man-loving gene" is inherited by the son through the X chromosome of the mother, and is found to code for attractiveness to males. The gene survives as a result of increasing female's fitness, as she is more attracted to males, and therefore creates more offspring (Camperio-Ciani, Corna, & Capiluppi, 2004). In some cases, this gene is passed onto her son and leads to homosexuality. Other supporting evidence for this hypothesis shows that homosexual men have more relatives in general on the mother's side, suggesting her increased fitness again (Camperio-Ciani, Corna, & Capiluppi, 2004). | + | This hypothesis was first conceived by an Italian researcher named Andrea Camperio-Ciani. He and his colleagues found that there is "evidence for maternally inherited factors favouring male homosexuality and promoting female fecundity" (Camperio-Ciani, Corna, & Capiluppi, 2004). In other words, they hypothesized that women who are very sexually active have a man-loving gene which makes them more sexually attracted to men and results in more offspring. This "Man-loving gene" is inherited by the son through the X chromosome of the mother, and is found to code for attractiveness to males. They believe this gene to be X-linked because of the observation that homosexual sons had more homosexual male relatives on their mother's side of the family compared to their father's. The gene survives as a result of increasing female's fitness, as she is more attracted to males, and therefore creates more offspring (Camperio-Ciani, Corna, & Capiluppi, 2004). In some cases, this gene is passed onto her son and leads to homosexuality. Other supporting evidence for this hypothesis shows that homosexual men have more relatives in general on the mother's side, suggesting her increased fitness again (Camperio-Ciani, Corna, & Capiluppi, 2004). The "Man-loving gene" would be a disadvantage in terms of reproductive fitness for the son, since he will not be passing on his genes to his offspring. However, the researchers believe that the benefit to the mother's fitness outweighs the cost to the son's fitness, so the gene is able to persist. |
| ==== Chromosomes Xq28 and 8 ==== | ==== Chromosomes Xq28 and 8 ==== | ||
