Well, all the legendaries are "genderless" and can't breed in game, but there HAVE been families od legendary pokemon, like Lugia in the anime, it's largely considered the "genderless" thing is jsut so people won't expect them to be able to breed. ALL legendaries are "genderless" in fact they make up most of the genderless group. Most fans consider them androgenous or hermaphrodites or both.
Well, all the legendaries are "genderless" and can't breed in game, but there HAVE been families od