"Explaining" it takes a lot a tact and time.It's not like a one time explanation and everything should be okay from there on.(hence just like explaining how sex works [?].)However, we still have to consider the environment we live in, ie neighbors, schoolmates, etc. No matter how well we have explained it there will be external factors that might lead the child into confusion.The former housemate once responded to me on the topic of my niece and some family issues, "Magtiwala ka kung paano mo pinalaki ung bata. Don't underestimate them."
sa mata ng bata, ang ginagawa ng nakatatanda ay nagiging tama...I guess, if a child grows up seeing two men in love with each other, the child will grow to think that that is just normal... isn't that what we want to happen? for people to start treating homosexuality as something that is as natural as heterosexuality? so why the need to explain this and end up appearing to be trying to defend your actions when it's just something that comes naturally?