What would you do if your son/daughter came out to you?
I find it that a fair amount of parents approach situations like this in a negative way and of course I would definetly accept him/her with open arms and demand meeting their partner [if they had one] lol. I think parents should be their child's number one supporter in these situations.
Tell them the rules have changed from "no boys/girls in your room" to keep the door open otherwise I'll have grandma give you the sex talk *shivers* reply