There is a story that a sister has a fight or something with her boyfriend (can't remember) if they break up or not. After she gets home her brother can tell she's angry or worried. She tells him she almost did it with her boyfriend in a public place maybe a greenhouse flower garden or something and left her panties there. They sneak into the little building find her panties but also they have sex. She becomes pregnant I believe.
Any other good stories where the brother or sister break up and for sympathy have sex with sibling and the sister gets pregnant.