Some aberrant varieties may produce siblings but ,by MYSTERY, these siblings do not necessarily follow their parent's sexual orientation.
Some may call it "infectious reproduction", "transgender reproduction", or the less famous "mysterious reproduction (often alt name for virgin conception/birth)".
Gay to dude: Antisexual reproduction.
Nerd: In a "not so far" future, Gays will overwhelm the guys.
Lesbo: Yeah, we'll pwn you!
Gay: Blame it on highly evolved form of reproduction, Antisexual Reproduction.