Nature, Nurture, and Sexual Preference A WEbpage by bryce byrd


With me being on the outside of the LGBTIQ community, I’ve always asked myself questions about those who are a part of that community: “What’s it like in places where people shun them,” or “Why do they talk like that?” But the question I would ask the most is: “Why are they gay?” This question naturally poses two different arguments: “Your sexuality is predetermined” or either “There are factors in your life that determine your sexuality.” These arguments are of the “nature vs. nurture” debate, but instead of siding with one or the other, I have a viewpoint that incorporates both of these sides, and that both nature and nurture work hand in hand to influence one’s sexual preferences.



I had found many interesting perspectives on reasons why some individuals are homosexual and why some aren't . One of the main causes that is strongly linked to homosexuality is too much or too little of a hormone, and how this fluctuation can affect sexual preference.


People holding the letters to "hormone"

Testosterone in men is needed for the development of genitalia, building of muscles, growth of facial hair, pubic hair, body hair, and mentality. Estrogen in women mainly does the same things as testosterone in men, but is mainly needed for the development of breasts and menstrual cycles. Watch this interesting video for more context.

However, when your body produces too much or too little of either male or female hormones, there are some very noticeable effects

Congenital Adrenal Hyperplasia

Congenital adrenal hyperplasia, is a genetic defect that happens in some girls where:

“the adrenal glands…enlarge prenatally and produce abnormally high amounts of androgens (male hormones)” (Lippa 122).

With these girls producing abnormally high amounts of male hormones, there are a number of studies that suggest that they CAH girls are often less content with being female and are more interested in being males than non-CAH girls.

Brain Structure Differences

A photo of the human brain...weird, isn't it?

Scientific researchers have also found some significant differences between a homosexual’s brain and a heterosexual’s brain. In a research study done by Dick F. Swaab, the suprachiasmatic nucleus, which regulates a person’s biological clock, is two times as large in homosexual men than in heterosexual men.

Dick F. Swaab

Another research study found the right brain hemispheres of lesbians are slightly larger—just like the right brain hemispheres of heterosexual men.




Epigenetics is the study how certain events in one’s life can cause genes to be turned off or turned on. Please watch this amazing video for context.

A researcher by the name of Dr. Tuck Ngun studied the genetic makeup of 47 pairs of identical male twins, and identified "epigenetic marks" in nine areas of the human genome that are strongly linked to male homosexuality. With this information, Dr. Ngun was able to predict homosexuality in individuals with an accuracy of close to 70 percent.

Look at this string of epigenetic code...isn't it enchanting??

Several scientific researchers have noted that epigenetics play a role in how cells respond to androgen, a male hormone, signaling. The researchers state that there are some genes that mediate androgen signaling, and that these genes are regulated by epigenetic modifications. They also say that the epigenetic marks can be passed down between generations.

Fraternal Birth Order Effect

The Fraternal birth order effect is, in men, sexual orientation correlates with an individual’s number of older brothers, each additional brother increasing the odds of homosexuality by approximately 33%. So the more boys a woman has, the higher the probability that they will be gay. Please watch this video for more context.

In a research study done with 944 men, some were straight and some gay. Out of all the men, some were twins, some were step-brothers, and some shared that same mother. The study came to the conclusion that for each male gestation (birth) that occurs, something changes in a woman’s body that makes her more likely to give birth to a gay son.



With both nature and nurture providing more strong evidence than ever before, most scientists have come to a stalemate when it comes to the nature vs. nurture debate. Those who have been arguing that there is only ONE factor into play, whether it’s on the side of nature or on the side of nurture, are heavily influenced. There are just way too many factors in an individual’s life that will determine sexual orientation. Because of this, I believe that Richard Lippa said it best:

"Gender results from a complex cascade of biological and social-environmental factors. Biological factors include genes, hormones, and neurophysiology. Social-environmental factors include family, peer, teacher, and media influences and the effects of social roles and institutions. Various casual factors constantly interact with one another; therefore, it is often difficult to precisely partition the causes of gender into two categories labeled nature and nurture" (Lippa 259).

Lippa’s statement embodies how nature and nurture are so intertwined with each other when it comes to sexual orientation, and how there are just almost limitless factors that come into play for one’s sexual preferences.


Created with images by PublicDomainPictures - "rainbow flag gay" • ChrisA1995 - "Nature" • IsaacMao - "Brain"

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