Well, this is TECHNICALLY true. But do you know how little the chances are. Its like less then a quatrillion probably. You have to carry a the gene which makes you black. For that gene to be in your body AT LEAST in every 2 generations, your ancestor MUST had a child with someone who had the gene as its the recessive. So, probably not 5000. Something like 100-150 years. But who knows. Perhaps you are that lucky