Are homosexuals really born with a preference for their own sex?

Yes, your brother is right.

Honestly, if you were half bright, common sense should tell you that no one would choose to be something that sees the person subjected to the intimidation and harassment that homosexuals are subjected to.

But don't worry about us in the western if we think we have it tough now and then. In some Arab countries upon identifying a gay person they force them to have a sex change, in others they drag you out to the local town square and hang you. Do some reading on gay rights in Uganda.

While the Russians send you to jail but not until the cops have their fun beating the crap out of you.

Honestly why would anyone choose this?

Well your brother's right, also you shouldn't debate something that you know "nothing" about.

I was debating about a chess strategies even though I suck at it and in the end kinda make a fool out of my self.

Well ask yourself this. Did you choose to be straight? did you make that conscious decision to like the opposite sex? Gay/bi people never chose to like and be attracted to the same sex. We did choose to date and be in relationships with them. But not to be turned on by them.

Plus, why would anyone choose to be gay/bi. And have to deal with the discrimination from family, friends, society, jobs, and religious people. And not being able to marry the person you love or being able to adopt kids, or donate blood. Not to mention having people automatically assume that you're infected with HIV, just because you're gay/bi . Nobody would just willingly choose to go through life like that.

Can you have any erection towards people of the same gender when they are naked? If you can have erection towards both genders, you are bi. If you can't, you are straight. If you can have erection ONLY towards people of the same gender as you are, you are gay (man) or lesbian (woman).

your brother is dead wrong

I was recruited at the age of 11 by adult homosexuals who apparently decided that I was ripe at that age.