I was suprised, that people still thinking how make Ichigo and Kaien a family, but I haven’t ever see a theory, that Ichigo is Kaien's son. So I've made one by myself.

Everything starts when Kaien’s wife- Miyako- becomes pregnant. Aizen Sosuke, who still wasn’t  a captain, have experiment in secret on child’s fetus. When a boy was born, Aizen want end what he has started. But he must remove from the way Kaien and Miyako, and Kaien’ s older brother- Isshin. By using his zanpakuto’s powers, Aizen  has trying to knit Kaien and Isshin in  to something terrible, like betray or murdering. But from some reasons Urahara Kisuke was framed, instead of Kaien. I don’t must know what a chaos was in Soul Society in these days. Some way Kein has discovered, that a mind behind this all want to kidnap his son. So when Isshin and his wife, Masaki must escaped from Soul Society to Earth, Kaien and Miyako give their child to they, to protect it. Isshin and Masaki have lived on Earth, and bring up litte Ichigo like their own child. In Soul Society Kaien has trying to prove, that Isshin  and Urahara aren’ t guilty. But when he has discovered something, Metastatica has appear. And we all know what happened next.

So, what are you thinking about this ?

PS: Sorry for my bad English. My English skills sux.