Animals are different. I will explain this since this is a lot simpler. If you know, and I am truly sure you do, men are attracted to curves. This is completely obvious, but I am not making this a joke. Legs, thighs, stomachs, chest, face, ect... it doesn't matter what, as long as it has the type of curves and if it's there.
For animals, it is similar, but different. Senses, as in smell and sight, are playing a big role for animals. They do not choose for gay or straight due to socializing, or anything of the sort. They are attracted to males or females of their species through smell most of the time. Aura if you will, for lack of a better term, will make the male or female (mostly male >.>) choose it's mate since it is attracted to that aroma.
Smell isn't the only thing that animals do to choose their mates. A sense of evolution is also a part of an animals preference. The harder beak, more vibrant feathers, tougher skin, more wins under it's belt... Whatever that would make the next generation better to survive and to continue this process. I must say that males that go together, in the animal kingdom, will most likely fail to make a great change in their evolutionary chain, but things happen. Females for animals will usually be worse off since it doesn't truly work perfectly due to their species' mating rituals/reproduction.
All in all, animals don't mate for love or to "get some". They do it to survive the next day, the next year, the next generation of their species. Good example, but different logic. You can place the "Survive" title on our preference as well, I suppose, but it's completely different since we have a more complex world and the ability to judge others. >.>
Also I never said you were trying to change my opinion, I was just saying that I would still stick to my opinion even if you are born with a hormone that is supposed to sway your preference. ^^