Board Thread:Questions and Answers/@comment-23856040-20131002063241/@comment-24001325-20131002221402

No, they are not. Both the Kurosaki and Ishida families were Echt Quincy (pure bloodline). And Ryūken's mother wanted to ensure the continued purity of her bloodline, so she brought in Masaki in to their home to make sure that she wouldn't get hurt and marry Ry�ūken. And yes, "Auntie" (Oba-san) is just a way of showing respect to an older woman.