A study identified physical characteristics associated with sexual orientation in men

Sexual orientation is a complex combination of biological, psychological, and social factors. A study published in the journal *Archives of Sexual Behavior* found that some homosexual men experience statistical biomarkers, which differ from heterosexual ones. These are doesn't mean...that sexual orientation can be “predicted” based on a person’s fingers or childhood behavior—this is more of a curious pattern that underscores the complexity of human sexuality.

Focus on This Study turned a Reddit user with the username psychologyofsex: “Исследование биомаркеров сексуальной ориентации показало, что мужчины-геи сообщали о том, что в детстве они в меньшей степени соответствовали своему полу, имели больше старших братьев, были более правшами, имели больше негетеросексуальных родственников и имели более феминизированное соотношение пальцев как на левой, так и на правой руке”.

As Doberman Media discovered, the study referenced by the Reddit user is titled “Биоразвивающиеся корреляции сексуальной ориентации у мужчин: данные из польской выборки” (researchers: Monika Folkerska-Zhukovskaya and Wojciech L. Dragan). Let's examine each biomarker separately.

"Feminine" Manners in Childhood

There is also another study on this topic: Lippa (2008) discovered...that gay men exhibit more pronounced feminine traits during childhood, such as an interest in traditionally feminine games, objects, and mannerisms.

Research “Биоразвивающиеся корреляции сексуальной ориентации у мужчин: данные из польской выборки” It states that gay boys are more likely to exhibit “feminine” mannerisms, show an interest in traditionally “feminine” games, and express their emotions differently than their heterosexual peers.

However, Larger-scale studies show that such differences are statistically significant but not decisive.

Having Older Siblings (Fraternal Birth Order Effect)

Now this is a more scientific fact. The more older brothers a man has, the higher the likelihood that he is gay. This phenomenon is called fraternal birth order effect and has been studied since the late 20th century. Scientists link it to the mother's immune response to male antigens during subsequent pregnancies.

Study: Blanchard and Bogaert (1996) found that each older brother increases a man’s likelihood of being homosexual by 33%. This effect is explained by the hypothesis of a maternal immune response to male antigens. / labs.psych.ucsb.edu

The Wikipedia article discusses the Fraternal Birth Order Effect in detail, confirming that having older brothers is associated with an increased likelihood of homosexuality in men. / Wiki

Important: It works only for men.
It does not predict orientation, but merely slightly increases the probability.

Finger Ratio (2D:4D)

This is a fairly old myth, but it turned out to be partly true. This is because the ratio of the index finger to the ring finger reflects prenatal testosterone levels. In gay men, the fingers may be more “feminized”—the index finger is longer than or equal in length to the ring finger. The effect is small, but noticeable in the statistics.

Lippa (2003) discovered...that homosexual men have a lower index-to-ring finger ratio (2D:4D) than heterosexual men. This may indicate the influence of prenatal androgens.

An article on PubMed examines the relationship between finger ratios and sexual orientation, confirming that homosexual men have a lower 2D:4D ratio than heterosexual men.

Right-handedness and Left-handedness

Also, the study “Биоразвивающиеся корреляции сексуальной ориентации у мужчин: данные из польской выборки” concluded that there are fewer left-handed men among homosexual men than among heterosexual men. Scientists are not yet sure why this is the case, but this observation has been confirmed by a number of studies.

In turn, other, older studies Research Blanchard and Lippa (2007) also failed to confirm the old hypothesis “Gay men are more likely to be left-handed”. It showed that This correlation exists among women (there are more left-handed women), and Among men, the opposite is true (there are more right-handers):

Here is an original excerpt from Abstract articles describing the key finding (quoted verbatim from the Springer website):

“Sexual orientation was differentially associated with lateral preferences among men and women. The associations among women were consistent with the predictions of the Geschwind–Galaburda theory, whereas among men they were consistent with the predictions of the callosal hypothesis.”

[перевод] The relationship between sexual orientation and hand and foot dominance differed between men and women. For women, the results were consistent with the predictions of the Geschwind–Galaburd theory (i.e., a higher proportion of non-dominant-hand users), while for men, they were consistent with the callosal hypothesis, meaning that pronounced right-handedness was more common among them.

• All of these signs are statistical correlations, not a “gay test.” They increase or decrease the likelihood, but they do not guarantee sexual orientation.