Without touching on the social aspects of the phenomenon, Lifehacker and N + 1 tell us what causes homosexuality and how it is explained from the point of view of evolution.
Achilles takes care of the wounded arrow Patroclus, the painting of the red-figured vase, about 500 years BC
Objective research on homosexuality among people is difficult. There are no reliable criteria for determining how much a person actually feels attracted to members of his or her gender does not exist (apart from a recent report on a neural network that, with a high percentage of hits, has learned to recognize Deep neural networks are more accurate than humans. facial images of gays in the face - however, even she makes mistakes).
All studies are conducted on samples, where participants themselves report their sexual orientation. However, in many societies, especially conservative religious ones, it is still not easy to recognize your choice, and often it is dangerous for life. Therefore, in the issue of studying the biological characteristics of homosexuality, scientists are forced to settle for relatively small samples of representatives of several ethnic groups living in Europe, the United States and Australia. In such conditions it is difficult to obtain reliable data.
Nevertheless, over the years of research, enough information has accumulated to recognize: homosexuals are born, and this phenomenon is common not only among people, but also among other animals.