You need to be careful, you are making a lot of swingeing generalisations from single incidents: a fallacy.
The incidence of homosexuality has ALWAYS been (throughout human and other animals) approximately 10% of the population.
Also, your three-arm example completely ignores evolution (one of your favourite concepts!). For example, look at your toes immediately adjacent to your big toes. If these toes are LONGER than the big toe, then you have a MUTATION. This is also a dominant genetic mutation, meaning that only one copy in the inherited pair needs to be a mutant for the person to express the gene (and carry it, obviously).
Please note that I am not suggesting that homosexuality is an evolutionary mutation (you naughty pranksters!).
This is just to assist you in your logical analysis of the genetic and/or environmental factors.
(I won't touch on the barefaced silliness of your wolf-pack analogy.)