To the heatedly debated nature vs. nurture question, Plomin’s Blueprint gives an unnuanced answer: it is the nature that makes you who you are.  According to the book, DNA explains half of the differences among us, in both physical and psychological traits.  At first glance, this verdict seems to leave at least the other half to the impact of nurture or the environment.  But here is the catch: the environmental effects are not only strongly correlated with DNA, but also unsystematic and unstable.  In other words, there is very little we can do about them. Your weight, for example, is almost 70% heritable (i.e., 70% of the differences in weight among a population come from genetical differences).   To cite another example that many might dismiss as a reductio ad absurdum, even your likelihood of getting a divorce has a heritability of 40%.

These findings have fascinating implications for society at large, especially parenting and education.  For one thing, those who are obsessed with getting their kids into Ivy League should know schools contribute only 2% to educational achievements.   In other words, excellent students produce excellent schools, not the other way around.  More importantly, parents have much less systematic impact on their children’s outcomes than they are led to believe.   Tiger moms should not expect their kids to be “blobs of clay that can be molded however they wish”.   In fact, kids are not even quite a blank canvas on which you can paint your favorite pictures. They are more like a canvas with a blueprint that your paint brush could either refine or ruin.

The book is an easy and enjoyable read, and the DNA literacy it tries to provide is well delivered and much appreciated.  Yet, I was sometimes taken aback by the tacit fatalism in the book. and wondered how it might undermine our commitment to good parenting.  I am also deeply troubled by the prospect of using genomes as a scientific fortune teller, to label and classify human beings at birth.

Nevertheless, the book does convince me that we are all fundamentally shaped by our DNA, more so than any other factors.  To me, this means life is like a constrained optimization problem for which we may choose the objectives but not the constraints.  That is, your free will can still decide where you land, so long as the target is within the feasible set.