Board Thread:Questions and Answers/@comment-25801533-20150531094407/@comment-32250158-20170629141218

If you click on the wiki page for soul, it states that souls can reproduce; therefore, souls can have children in the soul society. Which makes the fact that souls having families (such as Hitsugaya and his grandmother, and the clans) a possibility. Sure, if families die together, they would still be a family in the Soul Society, but if they don't it's highly unlikely that they would find each other; however, there are way too many families in the Soul Society for that to be the case. So, a soul can be born in the society too, which would explain familial resemblance and such. Kaien and Ichigo are cousins by blood; not just by means.