Everyone - whether they are black or white - can marry someone of the same race.
We've already been over this - race is determined by biology, and sexuality is determined by choice.
What you're trying to do is the same as comparing height to getting a DUI - one involves a biological factor, the other involves an active choice.
In case you aren't aware (and I'm sure you're not), that means you can't compare the two things accurately. There goes that entire argument, but knowing how stubborn you are, I'm sure it will continue anyway (though not with me because I've already shown it to be illogical).