[bgill]

About the “color” issue, I have to add that relatives might also look alike. I was doing some family genealogy and was driving through a town where my ancestors had once lived when I saw our family’s name on a storefront. Of course, we had to stop and go in. Well, low and behold, the owner came out and he was the spitting image of my deceased grandfather. No matter how much I showed the man, he claimed he wasn’t related. Yeah, whatever, dude. They could have been brothers despite being separated by several degrees of cousin-ship.

[Fred Nerks]

And therefor there's no doubt as to the paternity of Mark!

But frankly, 'David is quite another matter IMO.