A couple of weeks ago the New York Times Magazine published a feature article about the emerging field of behavioral genetics. The following passages stood out to me:

The most prominent finding of behavioral genetics has been summarized by the psychologist Eric Turkheimer: “The nature-nurture debate is over. . . . All human behavioral traits are heritable.” By this he meant that a substantial fraction of the variation among individuals within a culture can be linked to variation in their genes. Whether you measure intelligence or personality, religiosity or political orientation, television watching or cigarette smoking, the outcome is the same. Identical twins (who share all their genes) are more similar than fraternal twins (who share half their genes that vary among people). Biological siblings (who share half those genes too) are more similar than adopted siblings (who share no more genes than do strangers). And identical twins separated at birth and raised in different adoptive homes (who share their genes but not their environments) are uncannily similar.
. . . Behavioral genetics has repeatedly found that the “shared environment” — everything that siblings growing up in the same home have in common, including their parents, their neighborhood, their home, their peer group and their school — has less of an influence on the way they turn out than their genes. In many studies, the shared environment has no measurable influence on the adult at all. Siblings reared together end up no more similar than siblings reared apart, and adoptive siblings reared in the same family end up not similar at all. A large chunk of the variation among people in intelligence and personality is not predictable from any obvious feature of the world of their childhood.
.. .The discoveries of behavioral genetics call for another adjustment to our traditional conception of a nature-nurture cocktail. A common finding is that the effects of being brought up in a given family are sometimes detectable in childhood, but that they tend to peter out by the time the child has grown up. That is, the reach of the genes appears to get stronger as we age, not weaker.
Unfortunately, I missed the lecture by Dr. Miles Neale that Emily Herzlin wrote about this morning, but his focus on the purportedly strong parental influence on personal development sounds like an interesting counterpoint to the position expressed above.
The Times article goes on to stress that experts all agree that our personalities are indeed a “cocktail” affected by our parents and family, other early life experiences, genes, and our subsequent life choices and experiences. They differ only in how they weight the various factors. Nevertheless, if our personality traits are indeed as biologically determined as some people suppose, I can’t help but wonder about the implications for the effectiveness of various Buddhist meditations intended to foster particular qualities such as patience, kindness, and compassion.
What do you think?