Question

You learned about various theories surrounding the determination of one’s sexual orientation. In addition, you learned about some of the limitations and criticisms of the research.

Explain briefly (in 1-2 paragraphs) your understanding of the research on origins of sexual orientation.

Why is it important to understand what determines one’s sexual orientation? Consider ethical, legal, and social implications. If you do not think it is important to understand the origins, please explain.

Based on what you have learned in your readings within the class and your textbook, make a hypothesis as to where you think the research might lead.

Write your initial response to each part in 3–4 paragraphs. Support your arguments with research, applying APA standards to citation of sources.

Answer 1

GENITAL SEXUAL ACTIVITY WITH ANOTHER PERSON OF THE SAME SEX HAS BEEN recorded since antiquity. Fertility cults surrounding Israel were condemned by priests and prophets for utilizing both opposite and same-sex cult prostitutes in worship. Pederasty, the practice of men using young boys for sexual intercourse, was widely accepted practice in ancient Greece. The focus of the ancients was on human sexual behavior. The direction of a person’s inner sexual object-orientation is neither described nor contended.

During the middle ages, sexual intercourse with those of the same sex was considered sin. Those participating in same-sex genital activity were not thought to be differently oriented than those engaging in sexual activity with the opposite sex. Persons continuing in such same-sex activity were considered morally depraved.

In the seventeenth century genital sexual activity with those of the same sex was considered a crime. Such activity could result in imprisonment or hanging, yet the participants were not considered a different category of human beings.

Major changes occurred in the nineteenth century, shifting the consideration of same-sex genital activity to the nature, not simply the behavior, of the participant. In 1869 a pamphlet printed in Leipzig employed the term homosexualität in argumentation that would soon thereafter define homosexuality as mental illness—as a condition. It was not until 1892 that Charles Chaddock, an early translator of Krafft-Ebing’s classical medical handbook of sexual deviance, introduced the term homosexuality into the English language.1 Sexual inversion, the term most commonly used during the 1800s, referred to a broad range of deviant gender behavior. Deviant object-choice was but one of the many pathological symptoms exhibited by those whose sexual expression was at variance with that conventionally understood to be appropriate to one’s anatomical sex.

Early in the twentieth century medical doctors, particularly psychiatrists, viewed homosexuality as a pathological condition. Persons exhibiting homosexual behavior were considered immature, lacking in ego strength, arrested in childhood or early adolescent stages of development, or possessing paranoid and schizoid personality disorders. Understanding homosexuality as a pathological condition as well as “deviant” sexual behavior constituted a major shift in the understanding of the relationship of sex and sexuality to gender identity, gender roles, and a person’s essential being and place in society

Few issues are as hotly contested as what determines a person's sexual orientation. While most scientists agree that nature and nurture both play complex roles, the determinants of sexual orientation are still poorly understood. Current research into its underpinnings frequently focuses on the role of genes, environment, brain structure, and hormones.

The academy looked at several scientific studies with different focus areas that have all provided converging findings. These include family and twin studies. The studies have shown that homosexuality has both a heritable and an environmental component.

Family studies have shown that homosexual men have more older brothers than heterosexual men. Homosexual men are also more likely to have brothers that are also homosexual. Similarly, family studies show that lesbian women have more lesbian sisters than heterosexual women.

Studies on identical twins are important as identical twins inherit the same genes. This can shed light on a possible genetic cause. Studies on twins have established that homosexuality is more common in identical (monozygotic) twins than in non-identical (dizygotic) twins. This proves that homosexuality can be inherited.

However, the extent of the inheritance between twins was lower than expected. These findings contribute to the notion that although homosexuality can be inherited, this does not occur according to the rules of classical genetics. Rather, it occurs through another mechanism, known as epigenetics.

Epigenetics likely to be an important factor

Epigenetics relates to the influence of environmental factors on genes, either in the uterus or after birth. The field of epigenetics was developed after new methods were found that identify the molecular mechanisms (epi-marks) that mediate the effect of the environment on gene expression.

Epi-marks are usually erased from generation to generation. But under certain circumstances, they may be passed on to the next generation.

Normally all females have two X-chromosomes, one of which is inactive or “switched off” in a random manner. Researchers have observed that in some mothers who have homosexual sons there is an extreme “skewing” of inactivation of these X-chromosomes. The process is no longer random and the same X-chromosome is inactivated in these mothers.

This suggests that a region on the X-chromosome may be implicated in determining sexual orientation. The epigenetics hypothesis suggests that one develops a predisposition to homosexuality by inheriting these epi-marks across generations.

External environmental factors such as medicinal drugs, chemicals, toxic compounds, pesticides and substances such as plasticisers can also have an impact on DNA by creating epi-marks.

These environmental factors can also interfere with a pregnant woman’s hormonal system. This affects the levels of sex hormones in the developing foetus and may influence the activity of these hormones.

Future studies will determine whether these factors may have a direct impact on areas of the developing brain associated with the establishment of sexual orientation.

Looking to evolution

From an evolutionary perspective, same-sex relationships are said to constitute a “Darwinian paradox” because they do not contribute to human reproduction. This argument posits that because same-sex relationships do not contribute to the continuation of the species, they would be selected against.

If this suggestion were correct same-sex orientations would decrease and disappear with time. Yet non-heterosexual orientations are consistently maintained in most human populations and in the animal kingdom over time.

There also appear to be compensating factors in what is known as the “balancing selection hypothesis”, which accounts for reproduction and survival of the species. In this context, it has been demonstrated that the female relatives of homosexual men have more children on average than women who do not have homosexual relatives.

Future studies

The academy found that a multitude of scientific studies have shown sexual orientation is biologically determined. There is not a single gene or environmental factor that is responsible for this – but rather a set of complex interactions between the two that determines one’s sexual orientation.

However, more evidence is leading investigators to a specific region on the X-chromosome, and possibly a region on another chromosome.

The identification of these chromosomal regions does not imply that homosexuality is a disorder – nor does it imply that there are mutations in the genes in these regions, which still remain to be identified. Rather, for the first time, it suggests that there is a specific region on a chromosome that determines sexual orientation.

Although research has not yet found what the precise mechanisms are that determine sexual orientation – which may be heterosexual, homosexual, bisexual or asexual – the answers are likely to come to the fore through continued research. These findings will be important for the field of genetics and, more importantly, for those attracted to others of the same sex and society as a whole.