Can African Americans be Jewish?

Its ur life, religion is there for everone as long as u r convenced nd u belive enough in it. No one can controll u, later god will judge u not the coverment or who ever put the rules..... Simple, there are muslims African Americans, christians African Americans... etc. nd america support freedom as they say. So it should be the easiest country to do such things, nd again why is it illegal to chose the religion u want???