Another excellent new genetics book, but this one is largely about heritability a concept usually embraced on the right as a justification for their superior social position and rejected on the left as a cover for eugenics. But the author, a doctor of clinical psychology and a full professor at the University of Texas where she directs the Texas Twin Project, is a rare liberal whose clear explication of her own and other related work tells us the facts of life and explains why she feels that the limitations that nature places on our choices do not preclude attempts to achieve social equality. In fact, Dr. Harden explains that the knowledge of these limitations is what will enable us to help each other effectively.

The discussion includes clear explanations of GWAS, twin, sibling, and adoptee studies and also has many enlightening quotations from other academics in behavioral genetics on both, or sometimes multiple, sides of the significance of our genetic and environmental influences.

Some points that caught my interest are:

Are individual persons unique?
…each pair of parents could produce over 70 trillion genetically unique offspring..

What do GWAS studies have to say about inherited differences between racial groups?
Currently, stories about genetically rooted racial differences in the complex human traits relevant for social inequality in modern industrialized economies—traits like persistence and conscientiousness and creativity and abstract reasoning—are just that. They are stories.

Yet despite this nearly 1:1 correspondence between having exclusively European genetic ancestry and being racially categorized as White, or between having some African genetic ancestry and being racially categorized as Black, it would still be a mistake to conceptualize race as being synonymous with ancestry—for four reasons. [read them starting at location 1458]

How closely are we all related?
… how long ago in human history was the most recent common ancestor of all humans, i.e., someone who is in the family tree of everyone alive now. And the answer is—not that long ago: within the last few thousand years. One conservative estimate is around 1500 B.C., as the Hittites were learning how to forge iron weapons. But it could be as recent as around 50 A.D., right around the time that Nero fiddled as Rome burned. Go back a little further, to sometime between 5000 and 2000 B.C., as the Sumerians were developing a written alphabet and Egypt’s first dynasty was being established, you reach an even more remarkable point—everyone alive then, if they left any descendants at all, was a common ancestor of everyone alive now.

There are, on average, 33 of these recombination events that occur every time a genome is transmitted to the next generation. So, the 22 chromosomes that you inherited can be broken down into 22 33 = 55 different chunks, each of which can be traced back to one of your two paternal grandparents….So the chances that DNA from any one specific genealogical ancestor from nine generations ago still lurks in your genome is exceedingly small.

In what sense are we responsible for criminal acts and do we have free will?
Eric Turkheimer … proposed that this individuality in human outcomes, which remains after one has considered the constraints of genetics and family upbringing, is a way of “quantifying human agency.” His reasoning is this: We consider someone as having choice and control over an outcome if they could have done differently. If people who share the same accidents of birth—who have the same genetics (with the aforementioned qualifications) and the same family upbringing—never actually do turn out differently, it becomes harder to imagine that they could have done so. Unpredictability, in his view, becomes a sign of freedom: “The nonshared environment is, in a phrase, free will. Not the sort of metaphysical free will that no one believes in anymore, according to which human souls float free above the mechanistic constraints of the physical world, but an embodied free will ... that encompasses our ability to respond to complex circumstances in complex and unpredictable ways and in the process build the self.” In Turkheimer’s view, the individual phenotypic space that is not determined by either your genotype or the environmental circumstances defines the boundaries in which your free will gets to play. To borrow a phrase from the philosopher Daniel Dennett, [e-squared] lets you know how much “elbow room” you have to choose who [you are] going to be.

Other comments I noted:
Case and Deaton, for instance, argue that much of the blame for the immiseration of non-college-educated Americans can be laid at the doorstep of our exorbitantly costly health care system,

For instance, knowing that desegregating Southern hospitals closed the Black-White gap in infant mortality and saved the lives of thousands of Black infants in the decade from 1965 to 1975 requires, at a minimum, being able to quantify infant mortality.

The encounter proved the truth of the E. B. White quote that Frank used as an epigraph for his book Success and Luck: “Luck is not something you can mention in the presence of self-made men.” ( )

Terrific book about the strong role of genetics in human society, good explanations of basic genetic science, and the implications for deservedness both in the “lucky” and the “unlucky.” Too often the left viewpoint is to ignore genetics, or to decry it as a tool of eugenics. Too often the right embraces a simplistic or false view of genetics to justify exploitation.

She carefully explains why current data and methods aren’t good enough to say anything meaningful about comparing genetics for “ancestral groups” and why idiotic ideas about “races” aren’t useful (at a minimum) but doesn’t really get into other interesting/problematic issues like economic classes or castes or sex differences. ( )

I really wanted to like this one, but I'm not convinced the author made her case. Essentially the argument in this book boils down to two points: 1) Intelligence, work ethic and time spent in school (all traits that correlated with economic success in the US) correlate with the presence or absence of certain genes. 2) We shouldn't care about any of that. The problem I had with the book was it seemed the author was arguing that intelligence is genetically determined but we should still try to improve scholastic outcomes. Don't misunderstand me, I'm not advocating for leaving people with "bad" genes to starve in the streets, but if a certain type of intelligence is genetically predetermined wouldn't a better solution be improving the economic prospects of people with different types of intelligence rather than trying to work against their genes? ( )

Interesting though perhaps not fully convincing argument for liberals caring about DNA. Key point: existing research, largely carried out on white people, shows that genetic inheritance can explain about as much divergence in educational outcomes and perhaps even economic mobility as class can among otherwise similarly situated white people. What we don’t know, and what Harden argues we should study, is how this works for humanity in general, so that we can identify measures that can improve things for the worst-off in the genetic lottery, in Rawlsian fashion. Important sub-arguments: explaining individual variance within a population may often have nothing to do with explaining variance among populations; for example, in the US, being foreign-born is highly correlated with not being literate in English, but the states with the highest percentages of foreign-born residents also have the highest rates of English literacy, because immigrants tend to settle in states with high literacy, so knowing that there are a lot of foreign-born people in a state has the opposite relation to state literacy levels that you’d expect if you thought that individual stats predicted population-level stats. And discrimination can account for a lot of variation—when people with dark skin are denied educational and employment opportunities, the genes for dark skin will be correlated with bad outcomes, but not because they’re “genetic.” (Apparently research suggests that, until recently, genetic variation accounted for a lot less of the variation in white women’s educational attainment than white men’s, because opportunities were too limited for genetics to play much of a role.) So even if we explain a fair amount of variation among American whites (who, because of US racial categorizations, generally do have almost all European ancestry) with genetic variation, that doesn’t mean that it will explain variation among groups.

Likewise, causes can be genetic but solutions can be non-genetic: My myopia is largely genetic, even if aggravated by years of indoor reading, but my glasses correct both the genetic and behavioral parts of that. A specific genetic error causes PKU, which can permanently harm people who have it, but the treatment is not gene therapy but careful dietary management. Thus, Harden argues, a just society is one that gives to each person what they need to succeed under the conditions in which they find themselves, including whatever genes they inherited. Harden doesn’t really address what happens when the dominant group finds that project too difficult and prefers subordination instead, but I don’t think a geneticist could solve that one. The ultimate question is whether we'd do anything differently if we thought that genetic variation "explained" some part of intergroup differences, but since I agree that justice requires the answer "no," the real point of work like this is explaining to racists that they misunderstand science. ( )