Board Thread:Speculation House/@comment-174.88.131.94-20131012165729/@comment-3257939-20131111183551

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.