The Effects Of Prenatal Hormones On The Developing Fetus

Evolutionary psychologists have focused on Darwin’s principle of natural selection to explain the fact that genes interact and adapt to their surroundings. Their theory shows that in order to protect and promote the species’ survival, the genes interact resulting in individual personality traits, such as impulsivity and aggression. They further attempt to expand on this theory by saying that our genetics predetermine our mate selection and gender differences in sexuality. This fuels the debate concerning why we choose our mate, and whether or not the way we are raised will determine if will be heterosexual or homosexual.

One theory that many psychologist and scientist are trying to prove is that homosexuality has a fundamental biological basis. Similar to most mammalian species, humans at conception are females (McKnight 22). Toward the end of the first trimester is when the babies with a “male genetic message” begin to have small doses of two hormones, chorionic gonadotropin and luteinizing hormone, which start the altering process of the gonads into testes (McKnight 22). The hormones two jobs are to control the sexual development and control their function (McKnight 22). When the brain starts to develop masculine characteristics and lose the feminine characteristics, the processes are separate and occur at different

Mentioned is the chromosome Xq28 which is the region where scientists believe plays a key role in determining orientation, they found that 33 out of 40 brothers who were gay had similar inherited genes for chromosome Xq28. However, Bailey 's study on inherited genes is variable and limited, it does not explain the entirety of how sexual

A pattern emerges where the scholarly literature exploring this topic is largely focused on males. Reason being is that it appears that males are the sex who are predominantly homosexual in their orientation (LeVay & Baldwin, 2012). However, the sensitivity within the discourse of sexual orientation arises when it is debated upon whether one 's sexual preference is innate at birth, hence a force of nature or biology, or if it is a result of culture, nurture or environmental factors (Emmanuele et al., 2010). Furthermore, an experimental design will be proposed to further examine this topic. Comparing the three chosen studies, it is evident that a biological and endocrinological perspective does account for sexual orientation (Kraemer et al., 2006; Manning et al., 2007; Miller et al., 2008). Of the studies that currently exist on this topic, data shows that prenatal testosterone levels are indicative of sexual orientation (Kraemer et al., 2006; Manning et al., 2007; Miller et al., 2008). This paper addresses a topic that is relevant in today 's society; a topic that has, for the most part, been written off as having any scientific roots (Emmanuele et al., 2010). This paper counters that belief and in reading this essay, it will be evident that biology and endocrinology have a much stronger influence on sexual orientation than previously thought.

A highly debated issue concerning homosexuality is whether sexual-orientation is biologically determined or if it is a socially learned behavior. One case study done about this topic gathered that “the homosexual desire seems in most cases to be implanted in those who develop an unusually strong attachment for one parent” (Cory 1951:67). This seems to suggest that homosexuality can be influenced by family structure or other sociological elements. On the other side of this argument, there is the belief that people are born either gay or straight. Even though there is no scientific or genetic evidence to prove this, there have been many studies done and most homosexuals interviewed take this view-point. McIntosh states, “[homosexuality] is still commonly seen as a condition characterizing certain persons in the way that birthplace or deformity might characterize them” (1968:182). To support their cause and to fight for acceptance in society, it would be beneficial to convince people that sexual orientation is biologically determined. “Research indicates that people who believe that homosexuality is a choice are more likely to condemn it than are those who believe gays and lesbians are born that way”

If sexuality is developed at an early stage in a person’s life, then how does homosexuality occur? Homosexuality in Darwin’s selection theory doesn’t even exist. (Roughgarden, 2009, 127) Some say that it’s based on the person’s surrounding environment and influences while others say that it’s purely genetic. There has been substantial evidence that points to both genetic and environmental factors in developing homosexuality, but no one factor that clearly pushes over the top to define the origins of homosexuality. Statistically if a male is straight then there is a 4% percent chance that his brother might be gay, but if the male himself is gay, then the percentage jumps to 22%. (Roughgarden 2009: 247) These statistics simply show that gay males tend to group in families, it doesn’t necessarily point out anything specific about the environment’s effects or the male’s genetic makeup. (Roughgarden, 2009, 247)

The nurture concept of homosexuality include elements which influence a human’s sexual relationship likes social, parental and environment variables. A total opposite from the idea of the nature concept, a nurtured homosexual person is one that is “made” gay or lesbian.

In one article by Marcia Malory, “Homosexuality & Choice: Are Gay People ‘Born This Way’”, she goes into multiple studies on the genetics of a gay child's parents. A study conducted in 1993 the “gay gene” matter arose when it was looked into the homosexual children's parents having a different X chromosome marker. Nonetheless genes do not control our behavior completely as does environment. The brain may also play a role in sexual preference, like the study in 1991 showing the difference in neurons and pituitary glands. Later in the 2000s more studies showed that gay men have more symmetrical hemisphere and amygdala resembles that of women's. The brain develops in the womb and continues through late adulthood. When did a fetus choose its

There are multiple theories people hold on how they believe homosexuality started or is generally caused. However, after multiple studies and ongoing research the likelihood that it is nature, rather than nurture, based is going strong. Although, as of now, there has been no exact consensus among researchers, after examining possible genetic, hormonal, developmental, social, and/or cultural influences, to prove that homosexuality is completely one or the other, but it is usually found that people cannot choose their sexual orientation, but rather only

As it stands, there is no concrete evidence explaining why some individuals are homosexuals. There are however, two contradictory causes to homosexuality: (1) homosexuality is innate and (2) homosexuality is a choice.

Other studies conducted suggest that homosexuality might be base on difference in the brain structure of homosexual and heterosexual males. In 1991, Simon LeVay, a researcher at salks institute for biological studies in San Diego, found that an area of the brain called INAH-3 was larger in heterosexual men as in homosexual men [6]. INAH-3 is a small cell cluster in the hypothalamus that is involve regulating male sex behavior. LeVay’s finding provided clues that prove that sexual attraction to some extent might be biological. Other studies following levay’s study suggest that homosexuality might be base on genetic. It is believe that “gay gene” is passed from mother tho son.

Since homosexuality is said to be a behavioral trait then it can't be genetic. A behavioral trait is programmed by many genes rather than just by one gene. And the environment, these are just two of the many factors that that effect a behavioral trait. Whereas a genetic trait is affected by one gene, an example of a genetic trait is eye color. There are many ways of comparing genetic traits to behavioral traits but of all of the ways one could use ratios. For instance genetic trait has a ratio of 1 gene plus 0 environmental factors to 1 genetic trait, whereas a behavioral trait has a ratio of more than 1 gene plus more than 1 environmental factor to 1 behavioral trait.

It has long been debated where our sexual orientation comes from, particularly whether its biological or social forces driving these behaviors. In regards to homosexuality and bisexuals, some have argued that it may be a choice that these individuals are making.(Levay 2012: 41)Some have even said it is a mental disorder that one can recover from, but there is plenty of data that says otherwise.(Levay 2012: 41)(Levay 2012: 65) I believe diverse sexual orientations develop in humans due to sex hormones during fetal life, gene influences, and other effects such as birth order influences. I’ve come to this conclusion based on the narrative provided via Dr. Simon LeVay’s book Gay Straight, and the Reason Why, and the research that has been compiled showing strong influences from a multitude or reasons. I will also be looking at a research paper by Francesca Iemmola and Andrea Camperio Ciani, who looked into genetic factors influencing sexual orientation in men. It is clear there are gender differences between men and women, and this is probably one of the strongest indicators that hormones can affect the outcome of variations in gender traits.

If the argument of homosexual animals is not convincing enough, one must also consider the possibility of genetics. There is research suggesting that certain genetic markers on the x-chromosome are associated with homosexuality: “Using genetic mapping, the team found that a set of five genetic markers at the tip of the long arm of the X chromosome were identical in 33 of 40 pairs of homosexual brothers” (Journal Watch). This does not positively conclude that a person will be gay if he or she has these markers, but it does suggest that there are genetic factors at play rather than sexuality being merely a choice. Much of this research was done in 1993, and: “The same year, a study of twins found a significantly higher correlation of sexual orientation between identical as opposed to fraternal twins” (Bernstein 34). Two people with the same genetic makeup are more likely to both be gay or both be straight than two people with similar but not quite identical genetics.

A growing body of evidence the sexuality is due to biology, however this is still a controversy. Currently there is little understanding on the time period sexual orientation is programmed. One theory is that homosexual orientation is caused by atypical levels of hormones in utero (Mustanski, Bailey, & Kaspar, 2002 p 114). Research in the past has indicated that handiness is connected to prenatal androgen levels and studies have shown that there is a higher incidence of left handiness when mother were exposed to testosterone increasing agents (Bynny, Orth & Cohan as cited in Mustanski et al., 2002 p.114). One reason this theory has been suggested is that stress when pregnant is directly correlated to increased testosterone and left