User blog comment:Ajrep1994/Yang and Ruby are half sisters/@comment-3146930-20140723223108/@comment-3146930-20140724004707

Considering Yang and Ruby's close age, you have to wonder if maybe Yang's dad cheated on his wife/girlfriend and had Ruby, then took her in when Summer died. Of course they could have broken up and the dad kept custody, then he met Summer and she got preggo, but broke it off and went to raise Ruby on her on, also until her death and Ruby went to the father.