Because it's the only way they know how to express themselves. There are a lot of queer people who act closeted. But queer people being accepted into society is still premature and new. There's barely been any outlets for gay expression. The only passed down stereotype is being effeminate and breaking the masculine constructs. If you are a child and you grow up with malicious people, you might grow up malicious. Or perhaps less sympathetic. Any trait that might form from that environment. You become a variation of what you have been influenced by. It's the same for gay men and women. They grow up being gay. They are influenced by those like them. They can't necessarily control it. Especially the voice.