In Episode 19, Lincoln, Lynn, and Luan all cringe when the fanfic mentions Albert Skinny Dipping, however Lana and Lisa don't react. Why not? Well, Lana has done some pretty uncouth things in her time, so she might not have a problem with nudity, and Lisa has done things such as study poop and remove Lincoln's appendix, so she probably has no problem with anatomy.
In The Baby I Learned to Love, toddler Lynn mentions a "strange feeling in her heart". That's implied to be familial affection, but the wording makes it seem like she'd never felt it before. So does that mean that when Lynn was a toddler, she felt no affection towards her parents and older sisters?