Board Thread:Questions and Answers/@comment-24867665-20140426194343

Under Kurosaki Isshin's profile, it was listed that he was a former head of Shiba Clan. Now, from what I have read of the manga, Isshin couldn't have been. Shiba Kaien had two siblings, and since his death, Shiba Kuukaku, his sister, had been the new head of the Shiba Clan to this date. Seeing that Kaien also had a living younger brother, how could Shiba Isshin be the head of the Shiba Clan when there's already a head of the Shiba Clan?

Unless Isshin is Kaien's father? I haven't read anything that suggests that to be true.

However, Shiba Isshin could most likely have been a head of the branch family, like if Isshin and Kaien's fathers were brothers. 