Modern Science and Homosexuality
While homosexuals have often been derided by some for being "sick" or "disordered" in their sexuality, scientists have determined that sexual orientation is not determined by one single factor. Rather there are a variety of biological influences (genetic, hormonal, and environmental). Homosexuality is NOT caused by adverse psychological life events such as abnormal parenting or sexual abuse (1). More importantly, the American Psychological Association states “efforts to change sexual orientation are unlikely to be successful and involve some risk of harm.” (2)
An example of a genetic factor in determining sexual orientation involves the X chromosomes of the mother. In forming an embryo, the mother’s two X chromosomes are inactivated randomly to form a “mosaic” of cells in regards to which X chromosome was inactive at the time. A 2006 study shows that mothers with homosexual sons exhibit higher rates of skewing in terms of which X chromosome is inactivated than mothers without homosexual sons. 13% of mothers with one homosexual son and 23% of mothers with two homosexual sons exhibited this extreme skewing in the study. In comparison, only 4% of mothers without homosexual sons displayed this trait. (3)
Hormonal influences have also been observed in contributing to homosexuality. A variety of physical traits controlled by hormones have been observed to be on the whole statistically different in homosexuals and heterosexuals. A 2000 study found finger length ratio to be distinctive in people of different sexual orientations (4), and scientists have also observed that homosexual men exhibit on average a larger suprachiasmatic nucleus (a region of the brain responsible for controlling circadian rhythm) than their heterosexual counterparts (5a, 5b). Prenatal hormones influence both of these traits.
The third biological factor that comes into play is environmental factors. One of the most famous of these is known as the fraternal birth order effect. According to a 2001 study, each additional older brother increases the odds of following brothers being born homosexual by 33% (6). A 2002 study attributes 1 in 7 homosexual men’s sexuality to this phenomenon(7). Scientists believe that this factor is due to mothers becoming increasingly immune to H-Y antigens with each pregnancy. Antibodies to the H-Y antigens produced by the mother pass through to the fetus and impacts sexual differentiation in the developing baby (6).
The American Academy of Pediatrics stated in 2004 “current knowledge suggests that sexual orientation is usually established during early childhood." (1) This certainly appears to be the case. The genetic, hormonal, and environmental factors all seem to make their impact in the prenatal period, and are all very closely linked to one another. For instance, the environmental factor of having multiple older brothers has genetic consequences. Therefore, there is no “gay gene” or single cause for homosexuality, but rather an array of biological factors. As Americans begin to understand that homosexuality is not a choice but rather something biologically determined like skin color, homosexuals potentially stand to gain more rights and acceptance from those who have religious or social reasons for prejudice.
An example of a genetic factor in determining sexual orientation involves the X chromosomes of the mother. In forming an embryo, the mother’s two X chromosomes are inactivated randomly to form a “mosaic” of cells in regards to which X chromosome was inactive at the time. A 2006 study shows that mothers with homosexual sons exhibit higher rates of skewing in terms of which X chromosome is inactivated than mothers without homosexual sons. 13% of mothers with one homosexual son and 23% of mothers with two homosexual sons exhibited this extreme skewing in the study. In comparison, only 4% of mothers without homosexual sons displayed this trait. (3)
Hormonal influences have also been observed in contributing to homosexuality. A variety of physical traits controlled by hormones have been observed to be on the whole statistically different in homosexuals and heterosexuals. A 2000 study found finger length ratio to be distinctive in people of different sexual orientations (4), and scientists have also observed that homosexual men exhibit on average a larger suprachiasmatic nucleus (a region of the brain responsible for controlling circadian rhythm) than their heterosexual counterparts (5a, 5b). Prenatal hormones influence both of these traits.
The third biological factor that comes into play is environmental factors. One of the most famous of these is known as the fraternal birth order effect. According to a 2001 study, each additional older brother increases the odds of following brothers being born homosexual by 33% (6). A 2002 study attributes 1 in 7 homosexual men’s sexuality to this phenomenon(7). Scientists believe that this factor is due to mothers becoming increasingly immune to H-Y antigens with each pregnancy. Antibodies to the H-Y antigens produced by the mother pass through to the fetus and impacts sexual differentiation in the developing baby (6).
The American Academy of Pediatrics stated in 2004 “current knowledge suggests that sexual orientation is usually established during early childhood." (1) This certainly appears to be the case. The genetic, hormonal, and environmental factors all seem to make their impact in the prenatal period, and are all very closely linked to one another. For instance, the environmental factor of having multiple older brothers has genetic consequences. Therefore, there is no “gay gene” or single cause for homosexuality, but rather an array of biological factors. As Americans begin to understand that homosexuality is not a choice but rather something biologically determined like skin color, homosexuals potentially stand to gain more rights and acceptance from those who have religious or social reasons for prejudice.
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