Genetically speaking, Michael Jackson had the alleles that would have made his skin what we commonly call "black." However, he also developed a disease known as vitiligo. This caused the melanin production in his skin cells to stop and caused him to develop white patches. In severe cases of vitiligo, it may be preferable to depigment the rest of the skin rather than try to cover up the patches. Michael Jackson underwent this procedure, causing him to appear white. This is also the likely origin of his famous gloved hand.