I'd prefer to avoid any discussion of your opinion or moral stance on the matter, but I'm curious to know what your interpretations of its origins may be. This is an interesting topic for me because there seem to be so many factors, both biological and environmental that affect one's likelihood of being homosexual. I'll start with the biological aspects first, since those are the ones that I'm most familiar with.
There is very strong evidence for a genetic component to homosexuality, even though no correlating gene or gene group has ever been isolated or identified. It is well known that homosexuality is a naturally occurring phenomenon in many animal species and that there is a correlation between having homosexual relatives and actually being homosexual yourself, suggesting that it may be hereditary. This is expressed particularly well in breeding experiments with Drosophila fruit flies. Whenever a male fly is identified that attempts to mate with other males, he obviously does not produce any offspring of his own, but the rate of homosexuality in his nephews is far greater than that of the rest of the population.
Birth order also shows a statistically significant correlation with homosexuality in men, with the rate of homosexuality increasing proportionately to the number of older brothers (from the same mother). Obviously there are cases of older gay brothers and younger straight brothers, but this is the exception, not the rule, so don't bother trying to argue about it. Interestingly, the same effect is not observed with women. Female children are no more or less likely to become lesbians regardless of the number of older brothers or sisters they have, and homosexuality in male children does not seem to show any correlation with the number of older sisters. One theory is that abnormalities in prenatal testosterone exposure are amplified with each additional male fetus, which could affect the sexual orientation of future male children.
A study of the neuroanatomy of deceased heterosexual and homosexual individuals showed that homosexual male brains were less developed in one specific area than in the same part of a heterosexual male brain. Unfortunately, all homosexual brains in the study were taken from men who died of AIDS, whereas none of the heterosexual men had AIDS at their times of death. Consequently, it becomes impossible to determine whether the reduced size of the brain area is directly related to homosexuality, or if was simply the result of AIDS related neurodegeneration.
One environmental factor to consider is social acceptance. People are more likely to admit to their own homosexuality in an environment in which gays are not penalized for their lifestyle. Ironically though, homosexuality is actually more common in societies in which it is not allowed, as homosexuals feel obligated to acquire heterosexual relationships, thus increasing the frequency of the gay "gene," within the population. Also ironic is the fact that homophobia is strongest in individuals who are either extremely religious*, uneducated*, or who fear that they may be gay themselves.
The most puzzling piece of the homosexuality debate, for me at least, lies with a friend of mine who is straight, while his identical twin brother is gay. This is particularly interesting to me because as twins, birth order would make no difference as it is not determined until after the embryonic hormonal exposure has already left its influence. Furthermore, as identical twins with presumably identical embryonic hormonal exposures, they should be equally biologically predisposed to homosexuality... but they aren't.
What is your interpretation of these data and which do you think plays a greater role in the "nature vs nurture" debate on homosexuality? Also, since I only have one short paragraph on the "nurture" impact on the subject, please feel free to make suggestions or point out anything that I may have missed.
I apologize for not citing any sources. All data and studies referenced are from my notes from classes like Human Sexuality, Evolutionary Psychology, Biopsychology, and Behavioral Biology.
* not related, but religiousness and education show a strong inverse correlation, ie. more religious people are on average less educated than their less / non-religious counterparts.
There is very strong evidence for a genetic component to homosexuality, even though no correlating gene or gene group has ever been isolated or identified. It is well known that homosexuality is a naturally occurring phenomenon in many animal species and that there is a correlation between having homosexual relatives and actually being homosexual yourself, suggesting that it may be hereditary. This is expressed particularly well in breeding experiments with Drosophila fruit flies. Whenever a male fly is identified that attempts to mate with other males, he obviously does not produce any offspring of his own, but the rate of homosexuality in his nephews is far greater than that of the rest of the population.
Birth order also shows a statistically significant correlation with homosexuality in men, with the rate of homosexuality increasing proportionately to the number of older brothers (from the same mother). Obviously there are cases of older gay brothers and younger straight brothers, but this is the exception, not the rule, so don't bother trying to argue about it. Interestingly, the same effect is not observed with women. Female children are no more or less likely to become lesbians regardless of the number of older brothers or sisters they have, and homosexuality in male children does not seem to show any correlation with the number of older sisters. One theory is that abnormalities in prenatal testosterone exposure are amplified with each additional male fetus, which could affect the sexual orientation of future male children.
A study of the neuroanatomy of deceased heterosexual and homosexual individuals showed that homosexual male brains were less developed in one specific area than in the same part of a heterosexual male brain. Unfortunately, all homosexual brains in the study were taken from men who died of AIDS, whereas none of the heterosexual men had AIDS at their times of death. Consequently, it becomes impossible to determine whether the reduced size of the brain area is directly related to homosexuality, or if was simply the result of AIDS related neurodegeneration.
One environmental factor to consider is social acceptance. People are more likely to admit to their own homosexuality in an environment in which gays are not penalized for their lifestyle. Ironically though, homosexuality is actually more common in societies in which it is not allowed, as homosexuals feel obligated to acquire heterosexual relationships, thus increasing the frequency of the gay "gene," within the population. Also ironic is the fact that homophobia is strongest in individuals who are either extremely religious*, uneducated*, or who fear that they may be gay themselves.
The most puzzling piece of the homosexuality debate, for me at least, lies with a friend of mine who is straight, while his identical twin brother is gay. This is particularly interesting to me because as twins, birth order would make no difference as it is not determined until after the embryonic hormonal exposure has already left its influence. Furthermore, as identical twins with presumably identical embryonic hormonal exposures, they should be equally biologically predisposed to homosexuality... but they aren't.
What is your interpretation of these data and which do you think plays a greater role in the "nature vs nurture" debate on homosexuality? Also, since I only have one short paragraph on the "nurture" impact on the subject, please feel free to make suggestions or point out anything that I may have missed.
I apologize for not citing any sources. All data and studies referenced are from my notes from classes like Human Sexuality, Evolutionary Psychology, Biopsychology, and Behavioral Biology.
* not related, but religiousness and education show a strong inverse correlation, ie. more religious people are on average less educated than their less / non-religious counterparts.
I do believe that homosexual behavior in one's surroundings can influence homosexual behavior.
