Christopher Ryan doesn't buy a new theory on why gays exist:
The currently dominant theory turns on self-interest, as is the case with most current evolutionary thinking. Gay men, the theory posits, will be much more nurturing of their nieces and nephews than would heterosexual men (who would, after all, have their own kids to worry about). Thus, in increasing the reproductive potential of their nieces and nephews (by helping more of them survive to adulthood), a fraction of the man's DNA is carried forward to future generations....[T]his theory seems to be bending over backward to account for something that really needs no explanation.
Human sexuality in pre-agricultural societies was likely to have been more about maintaining relationships than about basic reproduction itself. Don’t believe me? E. O. Wilson, the founding thinker of what’s come to be known as evolutionary psychology, wrote that homosexuality is “above all a form of bonding,” and that, like “the greater part of heterosexual behavior,” homosexuality is “a device that cements relationships”
It is as natural as anything else on God's earth.