How is it that gays can play it straight, even in the bedroom?

Reading this question here, this passage in particular, I did grow up, got married hoping it would cure me, and had three wonderful children, and it was not the first time I have heard such a thing, it always makes me wonder how do they do it? As a straight male, I could never play gay. You could tell me I had to play gay for just a week for $100,000,000,000 I could not do it. There is no place mentally I could put myself to swap spit with another dude much less get freaky in the sheets. How does a lesbian or gay man find a way to play it straight, even to the point of having children and raising them as a nice straight couple? If you know you are gay and want to be with another woman or another man, how do you get intimate with someone from the other sex, and do so, on an ongoing basis?