Homosexual behavior is common in many animal species. As to whether this behavior has evolved to perform some kind of useful social function, like strengthening social bonds between members of the same sex, or whether animals do it simply because it presents another opportunity to do something they enjoy, is open to speculation.
Some evolutionary scientists say that human homosexuality may have evolved because of the benefits of having additional non-reproductive members contributing to the needs of the wider community. They say that as long as enough people continue to breed then there would be very little evolutionary pressure against homosexuality.
Others say that the flexibility of the human brain and the wide range of reactions to early childhood experiences will naturally result in a wide diversity of adult sexual behaviors. They say that homosexuality is common because it unites a diverse minority of people, giving them an opportunity to fulfil their physical and emotional needs, in the same way that the diverse majority of straight people are united by their heterosexuality.
From this point of view, the commonality of homosexuality would be largely cultural.
Evolutionary scientists should be very careful about making any unprovable claims about whether homosexual inclinations are biologically determined or formed through experience. Like every other victimized minority, the social status of the gay community rests entirely upon its political power. Frivolous theories of homosexuality, whether scientific or religious, have the potential to be abused as propaganda in the power struggle against gay freedoms.
Discrimination and oppression
Throughout history, in most parts of the world, homosexuality was a crime and those who were discovered were either arrested or killed. Even in the mid 1900s, the prisons of Europe and America were full of otherwise innocent men and women convicted of homosexuality, and those who were able to avoid arrest were often blackmailed by opportunists who knew their secret.
During the Great Social Revolution of the 1960s and 70s, as women were gaining equal rights and institutionalized racism was coming to an end, in the big cities of the western world, gay activists began to publicly protest against their continued persecution.
Street demonstrations were often broken up by baton wielding riot police, and many gay rights activists were beaten to death. People who witnessed this brutality on television were sickened by what they saw. The long suffering gay community soon gained the sympathy of the masses. Eventually the laws against homosexuality were repealed, and despite the continuing influence of traditional religion, the conservative culture of gay discrimination is gradually losing support.
Attitudes towards homosexuality continue to be a battleground between cultural tradition, social necessity, individual needs and desires, the dictates of ancient religious scriptures, the political activism of the oppressed, the prejudice of the unenlightened masses, and the sympathies of freethinking liberals.
Whether you like it or not, in the evolutionary jungle, almost anything is possible. And in the world of human politics, the laws are written by those with the power.