You cannot take a few examples of extreme free speech and use that to define a group of 1 billion people. This is like throwing out most of the data, so very limited data fits your desired curve. That is not how science works. This is more how propaganda works.
If you look at evolution, it is based on natural selection and sexual reproduction. Natural selection results in the best examples being chosen. While reproduction allows this to become engrained in the DNA. If you were selected, but do not breed, you are not fully part of evolution, since both factors need to be applied.
By its very nature, homosexual is not part of evolution, since this behavior cannot breed itself, into the DNA pool, to make it a part of the permanent evolutionary record. This implies homosexual is not natural; product of natural selection and evolution, but more of a cultural phenomena. It is more connected to will, choice and psychological inductions.
I am not making a value judgement, but this distinction is needed to make sure we approach this in a rational way, not based on genes that are not there, but based on cultural inductions. Homosexuality is connected to a long term cultural systemic affect, that appears to be part of all cultures, but is not fully conscious. This induction tends to produce the same result, generation after generation all over the earth.
My guess is homosexuality is connected to the observation of the strong bonds between mother and son, and father and daughter. Say these bonds were very close, a son's potential wife or a daughter's potential husband may create jealousy in their close parent, if there appears to be an alienation of affection. But if they become part of the other team; homosexuality, there is more security for the parents; remain number 1.
Mothers often make life hard on their son's wife, unless she is with the matriarchs program. But if the son's wife is willful and she has her own agenda, the son will be placed in the middle having to choose, even though he loves and chooses both. The Father and his daughters husband have similar dynamics. From the POV of a son or daughter dating, and getting this treatment, the solution to make peace for all may require playing on the other team; homosexual. The mother is less likely to stand in the way or sense alienation of affection; extra son to love.
After the breakup of the nuclear family, with the father often not present, the mother-son connection would have become stronger, than the father-daughter, due to living arrangements. One would expect a rise in gay inductions to help maintain the bond with a lonely mother without a mate. The daughters will lose their father and become closer to the mother, but have some trust issues with males. Two different affects.
In the Bible, gay behavior is frown upon, but lesbian is not really mentioned. I would attribute this to war and the father not around, leaving behind women and children, so the family break up scenario above plays out. Women remained more like women; Adam, while young men were altered by lonely woman; Eve. This affect also led to recruits for the church; celibacy. It is part of human nature gone astray due to will and choice.