Board Thread:Speculation House/@comment-174.88.131.94-20131012165729/@comment-4010415-20131111184654

DiegoAnime3000 wrote: ChishioKunrin wrote: Yeah, Monty said they're blood related, not step-sisters, and not cousins. And yet, they have different surnames and different appearances. If Summer Rose exists then she is related to Ruby but not to Yang.

...So let's say they are blood-related but not 100%. Like: same dad, different moms. Like, after Yang was born, her mom split, and then Ruby was born and her mom later died. Maybe she was born before the two got married, or.. something. I dunno. At least Monty said we'll find out why they have different last names in the show.