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hy do homosexual men have different brain structures than heterosexual men
Scientists continue to conduct research into the biological links to sexual orientation, and although the causes of sexual orientation are not yet clearly understood, it is hypothesized that it is caused by a complex interaction of genes, hormones, and environmental influences. Especially for men, the evidence for the influence of the postpartum social environment on sexual orientation is weak. Biological theories have gained favor in the scientific community because they reflect the causes of sexual orientation.
Sexual orientation may be shaped by genes, early uterine environment (e.g., fetal hormones), and brain structure.
This is one of the most important hypotheses for the formation of sexual orientation in terms of fetal development and hormonal influences. In short, the initial state of the developing fetal brain is "female". If the fetus receives enough testosterone, INAH3 (interstitial nucleus 3 of the anterior thalamus) will become larger and is associated with typical male sexual behavior. However, if adequate testosterone is not received, it may lead to the formation of same-sex attraction.
Studies show that INAH3 in homosexual men may be exposed to lower testosterone levels than in heterosexual men.
Many experiments have also shown that the mother's immune response during fetal development may cause homosexuality or bisexuality in men. As the number of sons a woman gives birth to increases, the likelihood that later-born sons will develop homosexuality increases significantly, a phenomenon known as the fraternal birth order effect. This effect is thought to explain between 15% and 29% of male homosexuality, according to research.
Differences in brain structure
In terms of brain structure, the sexually dimorphic nucleus (SDN-POA) is a key region that differs between sexes in humans and many mammals. Studies have shown that INAH-3 in homosexual men is significantly lower than that in heterosexual men. This phenomenon shows the difference in the sex-dimorphic nucleus in the brain development of homosexuals, which leads to our understanding of sexual orientation.
Scientific research has long confirmed the close connection between certain brain structures and sexual orientation.
Research into genetic influences suggests that a variety of genes may play a role in sexual orientation. Using the twin research method, scientists have conducted a large number of analyses, and the results show that identical twins are more similar in sexual orientation than fraternal twins, suggesting the potential influence of genes on the formation of sexual orientation.
Further research directions
In the latest study, scientists used genome mapping to explore the contributions of multiple genes to sexual orientation. Although science has not yet fully defined all the genetic factors that influence sexual orientation, researchers have proposed that there may be a "gay gene" on the X chromosome. This shows that the biological influence of sexual orientation is the result of the interaction of multiple factors, including genetics, prenatal environment and brain structure.
Research has shown that in some animal models, the formation of sex roles and attraction behavior is biologically driven.
Finally, although there is no precise scientific conclusion that can fully explain the differences in brain structure between homosexual men and heterosexual men, these studies show the complexity of sexual orientation formation and the possibility of more exploration directions in the future. With the advancement of technology, perhaps we will be able to gain a deeper understanding of this controversial and important issue. How many unknown factors are still influencing our sexual orientation?
