User blog comment:Godisme/My Take on Isshin/@comment-1044263-20100328130037

@Blazeltachi, you said that Ichigo always was a shinigami, but that's not true. He is a human with shinigami-powers, probably inherited from Isshin. But Masaki Kurosaki, Ichigo's mother, was definetly human, as she couldn't see Grand Fisher the night she died. I'm guessing that Isshin fell in love with Masaki in the human world, and that Ichigo is the child of a human and a shinigami. According to Rukia's crime earlier in the series, having a child with a human is probably a huge crime too, so Isshin had to hide, with the help of Urahara. Just to tell you, I'm guessing here!