how can human got black skin?  

Michael Jackson's children have light skin because the mother of the older two is white and the assumption is that the mother of the youngest is as well. Changing the color of your skin from the outside has no effect on the genetics that give your skin it's particular color.

theres a lot of rumors that his kids aren't genetically his for just the reason you said. Even with a white mother, there some da** unlikely genetics going on there

Micheal made kids from an Caucasian woman. That is why his kids look lighter than he does. Micheal is lighter now because of his skin disease. It starts with a V, but I can't say and spell the name of it. Micheal was born as a black man. He has had plastic surgery during the years to change the shape of his nose. His kids will look lighter than he does because of the woman that he laid down with and made babies from. I do personally think that Micheal has some mixture of another heritage in his family. Look at how light his sister Latoya is. And most of his family has good hair, especially his father Joe Jackson... I think that somewhere down the line his family is mixed with another race too.

Hi!
Genes aren't changed by plastic surgery, so our offspring would have the "old" ones. Michael Jackson's children were all born to white women, whose genes won the race!

It is a coincidence because the mothers were white and white genes aren't dominate or anything. even tho he was white on the outside, he still had black genes.

There have been a lot of rumours circulating over the paterninty of Michael Jacksons children, with a couple of guys steping forward to claim they are the paternal fathers to his children. Basically the colour of a baby is all down to genetics. Here you are assuming that the children should be darker, but why? Why could they not just follow the natural genetics of their mother?

I suspect if they did a DNA test there's not one drop of Jackson blood in those kids. Maybe the youngest, but that's very very doubtful.