You shouldn't need to explain!

You can just write about a young gay man because they are a person. If your protagonist were a young, straight man no one would ever ask you that question and if they did, you wouldn't have an answer. So you don't need to directly answer this question either.

A friend of mine who's a writer blames the characters themselves every time. If he were asked this question, he'd say something like, "I didn't make him gay. X was gay from the moment he walked into my head." I think most fiction writers externalize their characters to some extent that way.

In fact, I remember seeing the great SF writer John Brunner answering a question about his seminal 1964 novel "The Whole Man".

Gerald Howson, the book's protagonist, is a small person, walks with a cane due to orthopedic issues and haemophilia, and looks like a child at first glance, but he's actually not just a warm and even brilliant adult, it turns out he's the world's strongest telepath.

Howson starts off as a neglected child in what appears to be a collapsed America occupied and stabilized by the UN, and ends up becoming a respected member of society. Even though the book full of ideas and action, the central thread is Howson's desire to be accepted as a human by other humans - which is why it's called "The Whole Man".

I would sadly say that the society that we get a taste of is more civilized than the society we actually got. There are moments of compassion and warmth and strength in that book that make me cry every time.

Brunner was asked about Howson's disabilities, and he said something like, "He was like that from the beginning. I never conceived of him in any other way."

Great article, thanks for writing!