Mendelism is not magic

By Razib Khan | January 16, 2012 1:23 am

Michelle points me to this article in The Lost Angeles Times, The Colors of the Family:

I was holding my 1-year-old, ambling about downtown with some friends. White friends. She must have thought my boy belonged to one of them.

There’s a simple explanation: I’m black but my son, Ashe, is white. At least he looks it.

But things are more complicated than that.

I’m actually half black and half white. It should come as no surprise, though, that even as sophisticated as we’ve become about people of mixed parentage, I’m pigeonholed as black. If someone asks and I don’t have time to go deeper, that’s what I call myself.

Ashe is mixed too. His mother, my wife, Vanashree, is half white and half South Asian, with roots in India. She has olive skin, and Ashe is slightly lighter than she is.

This surprised us. When Ashe was born, one of the first things I said to Vanashree was, “Honey, he’s so light!” We chuckled, poking fun at our assumptions.*


Let’s get the sociological aspect out of the way. Is this really that surprising? Folk-biology has always had the concept of a “throwback,” which really distills the reality of Mendelian inheritance (as opposed to simple blending processes). In societies such as Brazil or India where there is a fair amount of segregation of polymorphisms which control skin color it isn’t that unheard of for a child to be darker or lighter in tone than both parents. And more frankly, this is not unknown within the African American community, where there is a range of skin tone due to ~20% European admixture. I suspect many African American would have these “assumptions,” because of an intuitive understanding of the unpredictable nature of the inheritance of this trait.

Second, the author of the piece is half black and half white in social terms, but there is no chance he is 50 percent African in ancestry. Barack H. Obama is 50 percent African in ancestry, but African Americans almost always have some admixture. I’ve analyzed ~150 African Americans in terms of their ancestry, and they always have some European ancestry. In fact the few Africans in my data set jump out because they lack this component. In other words, the author’s child is somewhat more than 50 percent European in ancestry.

Finally, what’s the science behind this? This isn’t that  hard to actually understand, because the genetic architecture of pigmentation has been well elucidated. Only a few genes control most of the variation across populations (the difference we see between Africans and Europeans, South Asians and East Asians). Because we know the parents’ ancestry we can make a few educated guess.es The largest effect size upon of a gene pigmentation in a given individual is probably from SLC24A5. The father is likely  a heterozygote on this at the SNP in question, with a “light” European copy, and a “dark” African one. The mother is most likely, though not inevitably, a homozygote; the frequency of the “light” copy is well north of 50 percent in South Asians (I’m a homozygote, as are both my parents). So the child has a 50 percent chance of being a heterozygote or a “light” homozygote. That’s some of the answer right there. Because the child does not have blue eyes we know that they are unlikely to be homozygote for the combination of markers which is correlated with blue eyes (probably due to a regulator element on the HERC2 locus). This is also associated with lighter complexion and hair color. But there is another locus which I think would be especially important: SLC45A2. There is a “light” variant here which is highly localized to Europeans. Its frequency is 95 percent in Northern Europe, and 15 percent in Northern India (85 percent in Northern Italy, 65 percent in Turkey, etc.). It is not found in East Asia or Africa, except in cases of clear admixture with Europeans. Europeans who are homozygote for the “dark” variant tend to be olive skinned (this genotype is relatively rare, though not unheard of in Southern Europe as per the frequencies above). Both the parents in this case would almost certainly be heterozygotes. This means that their son had a 25 percent chance of exhibiting the Northern European genotype. That is a straightforward explanation for why he might be lighter than either parent. Of course there are a few other genes of some importance, but I suspect that SLC45A2 is where most of the work is done in this case because of the backgrounds of the parents (i.e., I’m pretty sure they’re heterozygotes).

I understand that the point of the article was not the genomics of pigmentation. But to talk about social matters it sometimes pays to get the science nailed down. Like it or not this is a time in the United States where people of mixed ancestry are going to be more common. I rarely get the “Where are you from?” question anymore (because I’m not black or white), but I wonder if the “What are you?” (asked of mixed-race individuals) is going to persist a little longer.

* I think lurking within the subtext of the article is the salience of African ancestry, and the idea that it is particularly potent. The author’s wife’s background is mentioned almost in passing, before moving back to the main attraction of the child of an African American no longer appearing visibly African American. Many of the ideas of white nationalist thinkers such as Madison Grant may no longer be in vogue, but their idea that African ancestry was particular powerful in swamping out all other ancestry remains an unspoken assumption in American society.

MORE ABOUT: Genetics, Pigmentation, Race
  • Miley Cyrax

    “That means in most of America, most of the world, when he walks into a room filled with strangers, he’ll have nothing to prove. He will be assumed to be smart, trustworthy and reasonable.”

    Disgusting how the author just casually brands all of America as overwhelmingly racist against blacks without any support, like the fact is as self-evident as gravity. Don’t worry Kurt, I’m sure your son will still present himself as “Black” when needed, such as getting an extra 280 points on the SAT vis a vis Asians.

    @ Razib
    “I understand that the point of the article was not the genomics of pigmentation. But to talk about social matters it sometimes pays to get the science nailed down. Like it or not this is a time in the United States where people of mixed ancestry are going to be more common.”

    Right, the purpose of these kinds of articles is usually to serve as mental masturbation in cheerleading interracial relations and gushing about what a melting pot western societies are; the authors don’t care for science, nor do the readers. In this case, it’s also another excuse to promote the notion of an insidious, omnipresent white privilege.

    I’m a fan of interracial dating for my own personal life, but I find this kind of cheerleading nauseously fatuous.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    I’m a fan of interracial dating for my own personal life, but I find this kind of cheerleading nauseously fatuous.

    i’m on the same page as you. i found the author’s perspective personally off-putting, but it’s not too exceptional, and reflects the Zeitgeist.

  • Arthor

    I would have said that lurking within the subtext of the article is the possibility that the man in the article is wearing horns

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    #3, ?

  • Arthor
  • Miley Cyrax

    @ Arthor

    That would indeed be funny if it turned out to be a white guy’s kid, given the vitriol Streeter directs toward “white privilege” and his subsequent celebration that his son will be able to enjoy it.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    father is unlikely to be northern european. you can see via the kid’s photo.

  • jb

    I recently came across a picture of an actress named Rashida Jones, and I was struck by the mismatch between her name (which sounded African American) and her appearance (which looked very white to me). So I looked her up, and I discovered her father is Quincy Jones, a musician who looks very typically black . Her mother is white, but there is no suggestion of adoption or anything like that.

    I also found a slightly confusing article where Jones talked her hair. At one point she seems to describe it as “very fine, very straight,” but two paragraphs later it is described as “frizzy and fine.” Although I understand that the inheritance of hair types is less well understood than the inheritance of skin pigmentation, I was under the impression that while the children of people who were visibly “black” could be light skinned, they always had somewhat curly hair. It would be interesting to know what Jones’ hair would look like unstyled.

  • leviticus

    Will the writers’ grandchildren or great-grandchildren become proponents of “multiracial whiteness”? The founder(?) of this movement, A.D. Powell, seems a little unhinged, and racist, based on what I’ve read, but she makes a good point. It is possible that one can claim to be white and recognize that one has African ancestry, and not make a “big deal” about it. Plenty of people of mixed Asian and white ancestry already do it. And it isn’t simply about trying to pass and/or achieve white privilege. It can be a recognition of cultural or social affinity and phenotype. In simple terms, one is what people think they are, unless one wants to wear a t-shirt to the contrary.

    If I can offer the baby’s progeny any advice, keep a sense of humor about it all. My cousin laughingly recounts how once (early 1970’s) my grandad picked her up at her suburban (mostly white and East Asian) high school, people muttered “whose grandad is black?” Perhaps she should have been more serious and offended.

    And a brief peeve, if you are phenotypically white and mention you are part black, people can accuse you of trying to cash in on blackness but if you are part black and don’t mention it, then you are a passer and a race traitor, regardless of how negligible your African ancestry might be, particularly if you manage to be successful; white racists aren’t the only ones to push that one drop rule.

    I’ve seen two Oprah episodes that illustrate this wonderfully. One show had two phenotypically white women who claimed black ancestry and were harangued as opportunists. Years later, while interviewing Shirley T. Haizlip, author of the “Blacker the berry”, there was decided criticism for folks who “passed” as white.

    I can kind of understand the anger at pretendians as opportunists, but so far I’ve yet to hear of widespread Native American anger at individuals who “pass” as white. As A.D. Powell puts it, some people are just passing “for what you really are” or at least what they mostly are.

    Some folks can’t win for losing, the situation reminds me of the classic dilema Jews face with Anti-Semites- you’re d&mned if you are too asimmilated, you’re d&mned if you make a big deal about your identity.

  • http://ironrailsironweights.wordpress.com Peter

    It is possible that one can claim to be white and recognize that one has African ancestry, and not make a “big deal” about it.

    Not in America, with the One Drop Rule.

  • leviticus

    @Peter,

    I’d say increasingly it is a possibility. Moreover, the one drop rule, while a general rule, was not universally applied, and historically speaking it was applied inconsistently in space and time, being particularly virulent in the late 19th and early 20th centuries. In the early 19th-century in many Southern states, it was possible to legally be deemed white with a known percentage of African ancestry.

    Frank Sweet’s essay is a good read on this: http://backintyme.com/essays/item/7. Sweet is another important writer on this topic.

    Contra the common perception, which is based pretty much on the “tragic mulatto” literary theme, not every Southerner of passable appearance moved to the Midwest or upstate NY, changed their name and avoided contact with the Sun, or experienced a crisis of identity.

    My grandad, I mentioned in the above comment, considered himself, and was considered, white and Southern in his own community. His contemporaries were pretty much bigoted by any standard, some of whom displayed an almost humorous degree of cognitive dissonance between their own phenotype, or that of their spouse, and their attitudes.

  • http://www.hatzmeth.blogspot.com HM

    @leviticus, 

    You make an excellent point regarding the history of racial classification/the one-drop rule. In addition to Frank Sweet’s works, a couple of other good sources are What Blood Won’t Tell by Ariela Gross and The Invisible Line by Daniel Sharfstein.  

    As Gross said in a radio interview a few years ago:  “That idea of one drop of blood is a powerful idea that is now – in the . . . 21st century but beginning I think in the 20th century – a very powerful story in popular culture. But it wasn’t reflected in the law for most of our history or even in practice. One of the things I was surprised to find out is that not only did most states have for most of our history laws about fractions of ancestry that were much higher – more like one grandfather who was African made you a quote unquote a Negro – but that that didn’t really matter in court because the focus was instead on these aspects of identity that your neighbors could testify to: like your appearance, and your behavior, and who you associated with. And that holds true even into the 20th century . . .”  

    As Sharfstein wrote in Invisible Line:  “The law’s language could be confident with respect to race, but reality was more complex. A statute might draw a “bright line” – defining, as many state legislatures eventually did [in the early 20th century], anyone with any African ancestry as black. In practice, however, such laws were never crystal clear. Enforcing a color line to its logical extreme was impossible – it would classify as black people who by all appearances were white. . . . Drawing a line with the strictness of slavery, segregation, and white supremacy seemed to demand would have left very few people free of the fear that someone or some agency of the state could attempt to reclassify them. As a result, individuals and communities drew lines for themselves and for their neighbors that suited them best, often allowing racially ambiguous people to become white.”

  • leviticus

    @HM,

    It’s good that the reality is finally being discussed. My only fear is that it will be plagued by the sort of post-modernist, vicimitization, obfuscating rhetoric beloved of ethnic studies departments and the far right. While passing and tri-racial isolate communities make for an interesting history that says something important about the social construction of race, they remain a side-note and do not reflect the general experience.

    As you mention, HM, phenotype played an important role in determining status, although cognitive dissonance based on social affinities always complicated things. Crossing racial lines went both ways; while it was mostly black to white, people of entirely European ancestry could “become” black by association.

    I mentioned this in a post awhile back, but I don’t think the literature emphasizes it enough- the Jim Crow system, while a Modern development, was enforced by state and local bureaucracies that were hopelessly inefficient by 19th and 20th-century Western standards. The US South was not Nazi Germany or even 20th-century South Africa. Many counties simply did not have the clerical or technological wherewithal to enforce rules in rural neighborhoods, neighborhood in this instance meaning, as Southerners would define it, an informal territorial division not centered on a nucleated settlement. Southern dispersed residential patterns played an important role as a limitation on state control. (Trying to explain Southern residential patterns to non-English speakers from cultures with nucleated residential patterns is always fun. ‘No, I’m not from a town; I’m from near a town, no not a village. I’m from a county, it’s kind of like a district.”)

  • http://ironrailsironweights.wordpress.com Peter

    Last night I watched the 1955 movie Love Is a Many-Splendoured Thing on TCM. Loosely based on a true story, it involves a love affair between an American news correspondent and a woman doctor in 1949-1950 Hong Kong. The fact that the woman is of mixed Chinese and European ancestry, while the man is fully white, is highly relevant to the storyline. Today, of course, that sort of relationship would attract little or no attention. Even if the woman were fully Chinese it wouldn’t raise any eyebrows. We’re much more enlightened about racial issues today … but are we?

    Jennifer Jones, a completely white actress originally from Oklahoma, played the half-Chinese female lead. If casting of that sort were done today, there would be a massive outcry with accusations of racism flying everywhere. The actress would have to be half-Asian, or even fully Asian.

  • http://backintyme.com/ad221.php A.D. Powell

    I’d like to know what exactly about my views (see below) leviticus finds “racist” or “unhinged.”

    White Racial Identity, Racial Mixture, and the “One Drop Rule”

    http://melungeon.ning.com/forum/topics/5th-union-presentation-by-a-d-powell

  • leviticus

    That’s a more than fair question,

    and it’s just my opinion, and I’m just an anonymous voice on the internet.

    Before replying I asked myself if I was being uncharitable, but I have to return to my statement. If I was uncharitable it was because I made the statement without elaboration.

    I’d say the unhinged is the single-minded pursuit of the topic; the racism is based on what I perceive as hostility or stridency, but I will allow that with both accusations I may have been influenced by how other writers have characterized you; going along with the work of others was lazy, inexcusably so, on my part.

    You make an important point that African-Americans have played an important role in perpetuating the one drop rule, and at times were quite hypocritical about it, and I’ll say (oh Lord, where will this thread go) that Haizlip’s book was so hostile towards her relatives who passed, at times very mean-spirited, as to be racist. But African-Americans, historically, have been in a reactive role, although that has changed somewhat in recent years.

    You are putting the matter out there for discussion, along with Sweet starting an entire field of inquiry, all the while putting yourself in a place where your statements are subject scrutiny, which is far more than I have done or will do.

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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