Bleach Chapter -98

[Archangel]

Then again this may have been the first time a human ever became a shinigami so there would be no way for urahara to guess that hollowfication would occur

But honestly i like your theory better

[Tyreal]

Most people think that Uruhara used Hougyoku on Ichigo's father or young ichigo but there is no leads to suggest that Ichigo was shinigami before meeting Rukia.

Um how about the fact that Ichigo's father was a Shinigami? I'd consider that a pretty good lead which suggests that Ichigo had latent shinigami powers before he met Rukia. Not to mention the fact that he overcame Rukia's demon magic by shear will when he was still a human. And who thinks that Urahara used the Hogyoku on a young Ichigo? I've never heard that theory before.

Also it is stated by Urahara when he is training Ichigo to regain his shinigami powers that Byakuya only destroyed the powers given to him by Rukia, not Ichigo's own latent powers. I believe the process by which Urahara had Ichigo activate his shinigami powers also started him down the path to becoming a vizard, by awakening his inner hollow.

However another theory suggests that Ichigo's father was already a vizard (as opposed to an ordinary shingami) and the method Urahara used to have Ichigo regain his lost powers was <b>because</b> Urahara knew that Ichigo's father was a vizard and regardless of what he did Ichigo would turn out to be a vizard. In this theory the most likely thing that happened was that Urahara was the one to use the Hogyoku on Isshin in the past and this is why Isshin lost his powers.