Board Thread:Speculation House/@comment-174.88.131.94-20131012165729/@comment-18396318-20131024045757

Well, either both parents are Ruby's, both parents are Yang's, or they're one and one. It's pretty widely accepted that Ruby's mom is Summer Rose, and dead. That said, there's no indication of her dad being dead, and whenever one of the sisters talk about their parents, it's always Ruby about their dad. So I'd say the father is Ruby's. That would make the mother Yang's, but since Yang never seems to be upset about her father, there must have been a divorce, or maybe Yang is an illegitimate child of some kind.

So, my best guess is that Yang never knew her father, and after Ruby's mother died, her father remarried Yang's mom.