Part of the issue isn't that science says this or that, the problem is that too many people are too quick to judge somebody else for being different in some way. Whether it's genetic, biological, environmental, etc., why is it so hard to accept somebody or whatever or whoever they are, instead of condemning them based on a preconceived notion. Personality an character ought to be more of a deciding factor in how we relate to someone else IMHO.
Your willingness to be open to that sort of thing is a personality trait
You don't understand because you're probably at the end of the "open to new experiences" spectrum
If you deviate too much from the norm most people will have a natural revulsion to it. Have to be pretty open minded to just take everything the few hundred of million of us might do in stride.
I have no conscious* issue with gay marriage or queers doing what they want.
I still cringe away when i see gay PDA tho, my pure conservative soul can't handle it after years of indoctrination and just common behavior