Just curious. In looking at Sen. Obama or Tiger Woods who are 50/50 black (white) Obama / asian-Thai (Woods), you can tell they are a bit “different”, but the facial features are (to me) considerably more strongly black vs white or asian. Are facial features subject to dominance and recessiveness like other physical characteristics such as height etc.?
I lived next to a White kid in grade school whose facial structure and ears Obama reminds me of. 
It’s a form of subconscious racism. Don’t get me wrong, I am not blaming the OP; rather I think it’s still an issue in how white people (I am white) tend to perceive other races generally, but especially African Americans. I’d even go so far as to say it’s not malicious racism, but rather more an example of how ethnocentrically we still view world. We call Obama black, when he’s just as much white as he his black. Why do we do this? IMO it’s because we fixate on the “other”-ness–that is his non-whiteness. This is really sad because it suggests that we still think people as being either “white” or “something else”.
I second Spectre of Pithecanthropus. A friend of mine is a quarter Indonesian and three-quarters Dutch. She absolutely looks exotic to me, but her non-mixed Indonesian family thinks she looks Dutcher then Dutch.
Because in the worse case scenario, the KKK would want to hang him because he’s part Black. Which may merely be asking the question in another way. I think it has to do with the offspring of slave owners and slaves bing considered Black without regard to the amount of Caucasian genes lest they be able to inherit the plantation. It is learned from one’s ancestors.
A counter point is that at least in Western Cinema, the same prejudice holds for AmerIndians of mixed heritage.
A white former coworker of mine was married to a black man. His first wife had been white as well. His and the coworker’s daughter looked “typically” mixed. His older children were another story. The boy looked just like him, and his daughter was very white. Since there were three different outcomes with just one man, I’d wager there are a lot more mixed race folks we never suspect of having a parent who doesn’t look like them. We just notice the ones that look exotic.
Along that theme, counter to my Obama -Woods observations Lionel Ritchie’s daughter with a white wife/ mother, Nicole Ritchie, looks more 50/50 re her facial features. I guess you’re right it’s all variable depending on how the genes interact.
Some of this may be based on what you, personally, look for in face recognition. Have you ever had the experience of saying to a friend, “Hey, that guy over there looks just like George Clooney!” only to have your friend look at you like you have three heads and inform you that that guy over there is, in fact, Carrot Top, and looks nothing like George Clooney? My husband and I do that sort of thing all the time. I’ve learned that we simply notice different features, so if a pair has similar eyes and mouth, I’m more likely to say they look alike, whereas my husband will look first at the forehead, hair color and jawline. He absolutely cannot grok descriptions like, “She looks like Kirsten Dunst with dark hair!”
So you’re probably picking up on “black” in the features you normally view first, or most dominantly. Obama looks almost entirely white to me, with the only thing “black” about him being his skin tone in certain pictures and maybe a slightly wider than average nose. I have to really search his face and hair for “black features”. (He also looks exactly like a grown-up version of my high school sweetheart, who was a skinny white kid.)
Then again, it took me about three episodes to realize this guy’s black. (The character is biracial, I have no idea what the actor’s background is.)
Wentworth Miller is also half black, but could pass as a Mayflower descendant in any prep school in America. There are probably hundreds of “white” people you’ve seen in real life or on the internet who aren’t entirely white.
I’m not sure anyone would assume that either Obama or Tiger were of African descent if it weren’t for their skin color, and the fact that their backgrounds are well-publicized. I don’t personally think that Obama has very “typical” African facial features, and if you told me that Tiger was all Thai, rather than half, I would believe it without hesitation.
I disagree. I do think it’s a function of the faces that you’re used to seeing, though. If you’re used to looking at stereotypically “white” faces, you’re going to notice anything that departs from that. If you’re used to looking at stereotypically “black” faces, you’re going to notice anything that departs from that.
I would be surprised if a Black person, someone who spends much of their time interacting with other Black people, thinks Barack Obama (or any of the other biracial people cited here) looks Black.
For the record, Nicole Richie is Lionel Richie’s adopted daughter so it’s actually not surprising that she doesn’t look like him. 
According to her wiki entry, her background is a mixture of black, white, and Mexican, so that might be why she doesn’t appear to be as strongly African American as the other examples do to you - a smaller fraction of her background is black to begin with.
As for the issue from the OP, I think I agree most with cwthree’s take on this. The features that are different than what you’re used to seeing jump out at you. Since they do have some black traits from that side of their family, those traits are the ones that stand out the most to white people used to looking at other white people.
Genetics is a topic that gets very complicated fast, so I won’t try to get into it (since I’m not a geneticist and would be out of my depth). One thing I do know is that a lot of human traits (especially skin color AND also eye color, contrary to the simplified version of eye color inheritance taught in schools) are inherited based on the influence of MULTIPLE genes, so I definitely don’t think that this is about black people’s genes being dominant over white people’s genes.
The gene for brown eyes must be dominant. Consider James Earl Jones. Damned if I can find a picture where his eyes show up green, though.
I’d think black people probably have an easier time spotting biracial people who might “pass” for another race to the typical white person. It was totally obvious to me that the guy who plays in New Amsterdam is black, for example. Most black people grow up seeing non-stereotypical looking black all the time, in their neighborhoods, and at their family gatherings.
Of course, I have no proof of this, and there’s at least some confirmation bias at play, etc.
It would be nice if a person of Color would post. I always feel stupid discussing race with a bunch of other white folks.
My friend has a Chinese-Malaysian mother and an Irish father. Here, people comment on how Asian she looks but her relatives in Malaysia always say she looks so European. One customer in my shop asked for the Mexican girl one time :smack: .
I suspect they may look that way to you simply because you are not used to seeing many people of pure sub-Saharan African ancestry. Most blacks in the US have some admixture of European ancestry already. Therefore someone who is a exactly mid-way between European and African will appear to you to be more similar to African-Americans, because the latter are not entirely “African” looking. And you are probably not used to seeing anyone at all who is of African-Asian ancestry.
First of all, height isn’t a character that is subject to dominance and recessiveness. It is multifactorial, that is, the result of several different genes, and those genes generally show co-dominance, that is, people with two different alleles for a gene show intermediate characteristics rather than resembling one of the pure types. Most characters related to “racial” features are similar., that is, they do not show a simple dominance/recessive pattern of inheritance.
My sister (my family is Irish-German) is married to a Guyanan of African ancestry. Their children appear to me to be almost exactly intermediate in most characters.
Tiger Woods’s facial features don’t look particularly “black” to me.
My brother in law is half West African black and half Indian, and his facial features are visibly more “Indian.”
I bet if you were to take Barak’s skull and try to classify it racially (as forensic scientists do when they find a body), you’d get a pretty ambiguous answer.
If you were to lighten the guy’s skin, he would look pretty white to me.
I think the main thing that makes either Obama or Woods look African is their hair texture. With straighter hair Obama could easily be taken for North African or Middle Eastern, and Woods could be Malaysian.
I’m of mixed black (American black, so a healthy mixture to start with) and jewish heritage myself and while I cannot exactly pass, I look Hispanic more than anything - I have mocha skin, straightish brown hair, narrow nose & brown eyes.
My husband is a very white guy. In fact he actually is a Mayflower descendant. His whole family is blond and blue except his mother who is a true redhead with blue eyes.
Our daughter has blue eyes, blond hair and no “African” facial characteristics at all. Our son has curly dark hair and brown eyes and a slightly wider nose and lips, but is very fair skinned. They both could easily pass.