User blog comment:UFO Editor/Season 7 spoiler thread/@comment-1586735-20110318173141

RenatoB (an editor over at TV.com) has a FANTASTIC idea on why Felicia and Martha hate eachother, and why Felicia always acted so cold to Beth. He/she commented saying that Beth is really the love-child between Felicia and Mason (Martha's husband). And so Martha's husband was really Beth's father, which is why the two sisters didn't get along very well, and why Felicia is so resentful towards poor Beth, and when Martha died Felicia figured "hey, I screwed her husband and bore him a daughter, I might as well avenge her death to make up for it all" - this is such a FANTASTIC idea. And would explain why we didn't hear anything about Beth in Season 1 + 2 - yes, I know the writers hadn't created the character back then, but still.

A great idea I wanted to share with you all. Maybe the writers are using this idea. It'd make so much sense if they did!