TMZ Exclusive: We've learned Michael Jackson never adopted his three children, even though he's not the biological father.

We broke the story that neither Jackson nor Debbie Rowe are the biological parents of Michael Jr. and Paris. And Michael was not the biological parent of Prince Michael II either.

Now here's the rub. We've learned Jackson never filed legal papers to adopt any of his children. Legal experts tell us Jackson would be presumed the father but it's not conclusive by any means.

As for why Jackson didn't formally adopt -- we're told at the time the kids were born there was no third party whom he believed would try and claim custody. For some reason, Jackson never thought Debbie Rowe would mount a custody challenge.

Jackson/Rowe Not the Biological Parents

We've learned Michael Jackson was not the biological father of any of his children. And Debbie Rowe is not the biological mother of the two kids she bore for Michael. All three children were conceived in vitro -- outside the womb.

Multiple sources deeply connected to the births tell us Michael was not the sperm donor for any of his kids. Debbie's eggs were not used. She was merely the surrogate, and paid well for her services in the births of Michael Jr. and Paris.

In the case of Prince Michael II (the youngest), we're told the surrogate was never told of the identity of the "receiving parent" -- Michael Jackson. Three days after Prince was born at Grossmont Hospital in San Diego County, Jackson's lawyer came to the hospital to pick the baby up and deliver him to Michael.

We do not know if Jackson chose the sperm or egg donors or if he even knew who they were.

Although Rowe is not the biological mother, it's not a slam dunk that she would lose a custody battle. This type of case has never been litigated in California courts. Since Rowe was married to Jackson when Michael Jr. and Paris were born, there's a presumption that she's the biological parent. That presumption can be rebutted by other evidence.

We know there are documents outlining the whole arrangement for the birth of all three kids. Nonetheless, it's still an open issue with the courts.

Editor's Note: Us Weekly also reports exclusively this morning that the biological father of Prince and Paris is Arnold Klein, Jackson's dermatologist and Rowe's former boss.


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