It seems like the number of homosexual people in the modern world is growing rapidly with every year. Just looking at the U.S., from the east coast to the west coast, more and more pride parades pop up every year celebrating gay pride. Full towns have been recognized as gay communities such as Province Town in Cape Cod, Massachusetts. With the establishment of predominately homosexual events and communities, most would believe that the percentage of gay men and women is increasing with their growing stamp on society. This may, however, be merely an “illusion” due to the growing acceptance to alternate lifestyles which allows people to be comfortable with what has always existed. Is homosexuality really a choice more people are making these days or are people born with it? An overwhelming amount of the general public believes people choose to be gay, but this is not the case at all. According to Haider-Markel and Joslyn (2008), homosexuality is caused by numerous factors including an abnormal utero environment and genetics. With more research being done on the topic, the facts are piling up to further support that people are born into this world gay.
Camperio-Ciani et al. (2004) found that a gene on the X chromosome, Xq28, may be a possible carrier of a homosexuality gene and that homosexuality is passed along through maternal lineage. This gene is only believed to affect homosexuality in males. There is thought to be a genetic basis for female homosexuality, but the genes are less clear and it is most likely inherited in a completely different way than in men. The sisters of gay women did show a higher percentage for also identifying as gay, 12-35%, compared to only 2-14% of sisters of straight women. This is evidence that there is some genetic factor working in women, but scientists have not yet been able to hone in on the specific gene.
Camperio-Ciani also found that birth order has an effect on sexual orientation. In other words, with every male child you have, the chances the next male child born into a family will be gay increases significantly by 33%. Birth order having an effect on homosexuality means that the condition of the mother’s uterus, its hormones and the physical characteristics of the mother contribute to a fetus identifying as gay later in life.
Ellis and Ames (1987) documented several factors that can be traced all the way back to the womb. If testosterone or progesterone production are at abnormal levels during gestation, this may cause the developing person to be gay later in life. These two hormones are necessary for normal sexual development so a disturbance in either one may lead to abnormal sexual development. Ellis and Ames came to the conclusion, based on their studies about hormones in utero, that males are more likely to be gay for two possible reasons. The first reason is that because all fetuses start as females until males start differentiating into their separate sex, there is a chance for an incomplete transition from female to male causing the boys to have female-like tendencies. The second possible reason is that females are necessary for carrying offspring, therefore natural selection, a force that selects for or against traits, would favor females maintaining genes that minimally interrupt their reproductive success. Heterosexual women have a higher reproductive rate, therefore natural selection would maintain genes for heterosexuality as much as possible.
There have been experiments done to test what happens with the complete absence of hormones in adults to see if there is a change in sexual behavior. Genital manipulation has been successfully linked to changes in sexual orientation. After castrating male mice, scientists noted their behavior around both male and female mice. These castrated mice mounted the male mice instead of the female mice. In fact, the male mice seemed to ignore the female mice all together and exhibit homosexual tendencies. Based on these results, we can conclude that hormones at any stage in development, even out of the womb, can cause a change in sexual behavior.
Twin studies have played an important role in the study of homosexuality due to their ability to show evidence of both genetic and other biological factors taking effect. An interesting pattern has been discovered with both identical and fraternal twins and their likelihood for being gay. Franz J. Kallmann (1952) noticed that in fraternal twins, if one twin is gay, the other would most likely attest to having homosexual experiences at some point in their life. The other twin could, however be ranked on any level of the Kinsey scale from 1-6, 1 being completely straight and 6 being completely gay. In contrast, when grouping the identical twins of men that identified as gay based on Kinsey rating, every individual was a 3 or higher. Because identical twins come from the same egg, this study may show evidence of genetic basis for homosexuality where the data showing a pattern in fraternal twins may show support for an environmental cause of homosexuality.
According to Ellis and Ames, something as simple as stress level has also shown evidence for effecting sexual orientation. When a mother is put under extreme stress, those stress hormones are carried through the blood and can cross the placenta. Pregnant mice were subjected to high stress levels which led to the fetal testosterone level being affected. The resulting offspring were born with a sexual inversion, meaning they showed characteristics not stereotypical of their sex, such as homosexuality.
It seems like the factors contributing to homosexuality are endless as they emerge with modern research. The hope is that the public can be educated and the theories about homosexuality being a choice will be tossed out the window with the growing evidence supporting that people are born gay and all in all fabulous by nature.