In last Sunday's New York Times magazine, Steven Pinker wrote about the genetic bases of personality, and tells about having his personal genome sequenced (and posted on the internet).
His conclusion: A huge part of who we are is written into our DNA, behavioral as well as physical traits. But so many genes and their expression stir the pot of self that having a complete read-out of one's genome doesn't take one very far in knowing who we are. Having a partial scan to look for certain genes associated with disease, for example, might make sense, but paying $100,000 for all 6 billion A's, C's, G's and T's is a waste of money.
But personal genomes will get cheaper, and reading them will become more reliably predictive. So what? Knowing where we came from won't change who we are. The bushy-haired Harvard psychologist tells us he has a gene that predisposes him to baldness. What should he do? Shave his head?
The big philosophical question has been answered, with what may be the greatest series of scientific and technological breakthroughs of the last century-and-a-half. To a greater extent than we might care to admit, genes are destiny. If I've been happily married for more than half a century, it's not altogether because I am particularly virtuous, or because my wife is particularly lovable, or because I am imbued with particular "family values." It's at least partly because one particular sperm out of 200 million in one particular ejaculate won the race to one particular waiting egg, bearing a particular mix of genes that predisposed me to a stable relationship. It might help that something similar happened in the race that led to my wife's conception. Nature, nurture, and blind chance.
None of this changes anything. Pinker still has a bushy head of hair and I'm still mostly bald. We still struggle to make our way in the world with what we have. We still count our actions moral or immoral. We still try to raise our kids to conform to what we believe to be the best cultural norms. And meanwhile those strings of A's, C's, G's and T's go on doing their merry dance. There is no ghost in the machine, but the machine turns out to be more amazing than we ever imagined.