Lets say it is safe to assume that none of the 3 are biologically Michael's children. I have 2 questions about this:
1. Why did he not donate sperm himself for artificial insemination?
2. If he couldn't produce sperm, then why didn't he use a black donar?
He could have chosen a black male with a passing resemblence to himself and if he had done so people would assume the kids were fathered by him. I find this very strange.
Nobody has yet been able to answer these questions satisfactorily.
There was an interesting program about MJ called something like "The Chaning Face of MJ" who claimed a lot of his surgery was to do with psychological issues of him not wanting to resemble his father and if this is true, which doesn't sound unreasonable given what his father was like, then it would make sense that MJ didn't want the children he raised to look anything like his father too even if the result was that they looked nothing like him either.