For one, homosexuality exists. It’s unclear if it is a genetic condition, an environmental factor, or a combination of the two, but it exists. We are stuck with people that are not heterosexual.
Second, my respect for personal freedoms means that I don’t care what consenting adults do in privacy with each other. Or I should say, it’s not my problem. I have other things to worry about as long as they keep it private.
So when it comes to informing children about the concept of homosexuality, I think it is best to acknowledge its existence. That some people have a partner of the same sex and leave it at that. If a child asks how two homosexuals have a child, answer with adoption. If they are older (teenager), bring up surrogacy or sperm donation. Homosexuals exist, I don’t see their sexuality as a threat, and so it is best to instill a value of recognition to ensure that we all live our own lives in peace.