Biological Factors Of Sexual Orientation During Prenatal Development

Cynthia Lac
Many people will wonder how same-sex relationships occur, but not often do people wonder why most of the world is straight. People who study humans’ sexual orientation, don’t necessarily look at what makes someone gay or lesbian, but rather what causes it at all. During the very early stages of development, XX and XY chromosome fetuses, share the same traits (1). After 9 weeks, fetuses are given higher levels of testosterone to begin the process of a male-typical body. During prenatal development, there are biological factors that influence diverse sexual orientation in humans. Prenatal sex hormones are a good focus when looking at why humans are gynephilic or androphilic because experiments have been done on animals showing that
It important to look at gendered traits when studying sexual orientation because many children who grow up be non-gender conforming, typically end up choosing same-sex partners. There are mental and behavioral difference between boy and girls, even at childhood showing that gendered traits are an inborn component. Although gender non-conformity is a bigger sign in homosexual boys than is for girls. Women with Congenital Adrenal Hyperplasia (CAH) suffer from a genetic mutation that disrupts enzymes involved in manufacturing hormones that are made in the adrenal gland. This condition causes the glands to secrete higher levels of androgens, a testosterone-like hormone. In males this extra secretion of androgens has no noticeable effects, but for girls, it can be quite obvious. In more serious cases, girls with CAH, on average, are more aggressive and participate in more rough-and-tumble play in comparison to other girls. So one might conclude, that the causes of variation and sex-typed behavior in childhood are the same causes of variations of sexual orientation in adulthood (video gender identity and sexual
Research done by _ confirmed that men who are gay have more older brothers in comparison to straight men. The cause of the older-brother effect points strongly away from a social one because the effect doesn’t come directly from the older brother, but the mother. It is believed that the when the mother has her first born, her body remembers the male antigens from her previous pregnancy. The maternal immune hypothesis was presented by Ray Blanchard in VIDEO, which states that the mother’s body will produce substances to respond the foreign male antigens from her previous pregnancy, preventing the XY fetus from getting all their male specific antigens. The antigens carry at least 27 proteins, that are male specific. Some of these antigens have female counterparts, and some don’t. Blanchard suggests that because the male fetus is not able to receive all the usual male “typical” antigens, they are more likely to be gay. The effect has only been seen in gay men in correlation with older brothers and no other