Is it possible to become a tenure track Assistant Professor at the same university where I did Post Doc? I know that there is such thing as "intellectual incest" and that many universities are against hiring their own PhD graduates for their faculty positions.

But what about the movement from being a Post Doc to a Tenure Track Faculty at the same university? If a person did his PhD at University A, and did Post Doc at University B, would it be possible for the person to get hired as a tenure track faculty at University B straight from his Post Doc position? and if yes, why doesn't the "intellectual incest" apply in this case?

Thank you,
I think this might vary by institution, but for most, at least in the US, there wouldn't be any problem with such a move. Of course, you are unlikely to get any advantage in your application and regulations most places will require that you be treated like any other. 

I know of one situation like this in which the university really wanted to keep a post-doc so wrote the specification for the tenure track job that matched him nearly perfectly. Nearly everything except the Father's middle name. They sent out the required national search and got back three candidates (among many others) that seemed to be a better fit (on paper) than he was. But he got the job in the end. 

So, not impossible (most places) but likely no advantage either.