Bull shit. I know this dude who's a quadroon (1/4 black, 3/4 English) and he looks like a really generic white person. If you looked at him you would think "German" or "Polish" not 1/4 black. He doesn't even have black hair, never mind any of the facial features.
How's that bullshit? 1/4 black is pretty easy to tell in most cases, black genes are dominant, the phenotypes are pretty detectable, for me at least.
i got a half mexican friend that goes by "half mexican" and a half asian friend that goes by "half asian." when i was a kid, my half asian, whole asian, and white friends were in a band. i always thought it was kinda neat that it was a 3 person band...but exactly half asian.