So did heterosexuals parents not have anal? And that means bisexuals parents did but she DIDN'T like it?? Wait, what about asexuals?
But mom enjoying it would make both hetero parents sodomites, and I distinctly remember famous late homophobe Strom Thurmond once angrily protest on the Senate chamber floor that "Straight people don't do such acts!" He was promptly laughed off the chamber floor for his statement, but still.
asexuals have anal, too, but we call it a bowel movement. It's my guess that anal, among heteros, is an amusing joke but not widely practiced. I can't imagine a bi not liking it. I think that about covers the subject.