|Who Do You Think You Are? - Page 12|
In his efforts to show the biochemical roots of temperament, Kagan is no longer a voice in the wilderness. In the last decade alone, behavioral DNA researchers have identified genes that boost the likelihood of being shy, optimistic, attracted to risk, gregarious, distraction-prone, and several other temperamental biases identified by Chess and Thomas nearly 50 years ago. Predictably, these investigations have been overblown by the media, with headlines touting the discovery of a "shyness gene," a "happiness gene," and various other slices of DNA that purportedly bless or doom one to a particular behavioral or emotional fate. Many people, both in and out of the therapy field, have responded with instinctive distrust, wondering whether this outpouring of behavioral genetics news heralds a return to biological determinism.
This scenario seems unlikely. Many genetic researchers have taken pains to explain that no gene causes a behavior or emotional state, but merely renders one more vulnerable to it. Furthermore, no single gene appears to boost susceptibility by much. The fundamental goal of behavioral molecular genetics "is not aimed at identifying the gene for a particular behavioral dimension," writes Boston University behavioral geneticist Kimberly Saudino in the June 2005 issue of The Journal of Developmental Behavioral Pediatrics. Rather, the goal is "to identify many genes that each make a small contribution to variability in a particular trait."
Kagan's greatest hope, in fact, is that genetic and brain science will advance sufficiently to pinpoint the neurochemistry that causes high reactivity. With unusual candor for a scientist, he says, "For now, we have only theories. Maybe we'll find out that the critical action is not in the amygdala, but in its projections—or somewhere else entirely. We could be surprised. Nature is unpredictable." He sounds intrigued, rather than frustrated, by the menu of possibilities.
What he is certain of is that temperament is a complicated creature, at once plastic and persistent. Throughout the course of his study, most of his high-reactive youngsters became less timid and tense over time, while some of his low-reactive kids became quieter and more fearful. But the bottom line held: only rarely did individuals fundamentally change their temperamental stripes. Almost no sociable infants became deeply introverted adolescents; conversely, only rarely did a tense, fussy infant metamorphose into a relaxed, ebullient teenager. Most adolescents retained at least some qualities of their original temperament, especially regarding what Kagan calls the "feeling tone" that bubbled beneath their public behavior.