Eunuchs are men who have been castrated. Lets humor it being gays though, in the same passage where Jesus said that some were that way from birth, He also says that all those who cannot accept marriage being male and female were to remain celibate. It included the eunuchs.
While that makes a nice appeal to emotion, it makes a poor argument, its like saying why would anyone choose to be a pediphile, adulterer, murderer, or rapist? Surely those things would cause prejudice, and persecution in society.
They choose them because they loved their sin more than they love God and the love of the truth. They prefer the darkness, and in the sin of homosexuality specifically, men are given over to it, its a form of punishment - see Romans 1:24 Wherefore God also gave them up to uncleanness through the lusts of their own hearts, to dishonour their own bodies between themselves
No, we must consider what God says about it. Hes clear on it.
Does driving a school bus drunk become ok, because science shows a link that alcholism is genetic? Should we change laws to make drunkeness ok because they cant help how they were born?
Like it or not, there is no good argument for what God clearly defines as sin, there is no allowance under any argument for homosexuality. Its very practice is a punishment.