Behavioral Genetics

Pinker starts his chapter on children with the so-called three laws of behavioral genetics:

The First Law: All human behavioral traits are heritable.

The Second Law: The effect of being raised in the same family is smaller than the effect of the genes.

The Third Law: A substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families. The laws are about what make us what

Pinker, Steven. The Blank Slate: The Modern Denial of Human Nature (p. 373). Penguin Publishing Group. Kindle Edition.

The pillar of the Second Law is the evidence showing that siblings reared in the same family are at most only slightly more similar than siblings raised apart. He concludes from this that parenting choices have very small effects on children's development.

It seems to me that he is leaving out a very crucial aspect of the unique environment of a child reared with a sibling. There is only so much social/emotional ecospace in a family, and that fact induces siblings to choose different paths. If the first child is a hell-raiser, the second may become more docile to fill the empty spot in the family ecosystem, and vice-versa. Similar effects can occur for the math whiz, sports star, science geek, etc. If this difference in environment is as large as the effects of different parents it helps explain the fairly large Third Law effect and tends to discredit Pinker's version of the Second Law.

Comments

Post a Comment

Popular posts from this blog

Anti-Libertarian: re-post

The most pointed critique of social security and liberalism in general is the libertarian critique. The problem with libertarians, for a liberal, is that we have too much in common. We both believe in individual rights, tolerance of individual differences, and dislike government prescription of religion. The basic difference, it seems to me, is the different answers we give to Cain's (with thanks to the Captain - my original version had the corpse asking the question!) famous question: "Am I my brother's keeper?" That's not really my basic bitch against the libertarians though. My real complaint is the same as my complaint against most religion - its premise is a fraud. For those who can't stand to wait for the punchline, I believe that trying to implement libertarian principles leads to tyranny or social disintegration. Demonstrating that takes some historical (and pre-historical) context. For all but the last 15,000 or so of the 100,000 years the human spec
Read more

Uneasy Lies The Head

Uneasy lies the head that wears a crown ........... Shakespeare Henry IV, Part II. So it is with us and our slightly distant primate cousins , so it seems. A 9-year study of wild baboons in Kenya by Princeton University and the Institute of Primate Research may turn conventional assumptions of alphas males upside down. The study found that alpha males have high testosterone levels, which allows them to dominate other baboons, get access to more food, and attract better mates. This is expected. Surprisingly, though, the alpha males also have high levels of stress hormone glucocorticoid, which scientists measured from their feces samples. In fact, the stress of alpha baboons was on par with low-ranking baboons. The convention wisdom is that access to food and females provides life security and thus less stress for dominant males. Conversely, weak males who are constantly threatened by starvation and physical violence from stronger males are thought to be more stressed. The st
Read more

We Call it Soccer

The US played its best, and maybe only good game of World Cup, but lost thanks to brilliant goalkeeping by the Swedish keeper and the bizarre method soccer uses to settle ties when three US stars could not put the ball on frame from the 12 yard spot.  At the end it came down to a blocked shot that spun in by maybe a couple of centimeters. Well, that's football - too much like life.   Which brings me to a modest proposal.  Replace the thirty minute overtimes with as many 7-player 15 minute periods as needed to settle it.  Scoring should be much easier with fewer players.
Read more