Ancestry Magazine

In my ongoing trolling for my Rawlins roots, I came across a description of the Rawlins “temperament” from a 19th century historian. After a brief list of laudable qualities, he adds this tidbit: “If noted for any peculiarities worthy of mention they are, reticence . . . and for a commendable habit of not neglecting their own affairs for the purpose of investigating those of their neighbors.” In other words, we tend to keep to ourselves and mind our own business.

So is it mere chance—kismet—that I am reading a century-old description of a personality trait most people who know me would instantly recognize as, well, me?

Any family knows that offspring tend to look something like their ancestors. My brothers and I have blue eyes, and so do my younger brother’s children. My older brother’s kids have brown eyes, but if I say they got them from their mother, you know exactly what I mean.

And whether we think about the implications behind it or not, we also talk as though other sorts of traits are passed down. We say music, smarts, or a wild hair “runs in the family.” But how? Are the kids of smart parents smart because their intelligent parents teach them to be intelligent? My mother is rather quiet and reserved. So maybe I took my cues from her and am simply a product of my environment. But my mother is not a Rawlins, so this does not explain whether someone in 1870 actually divined anything about my personality.

The explosion of research into the human genome in the 1990s fathered the temporary notion that there was a gene for everything. Genes made you fat, genes made you smart, genes made you shy. Genes affected your tendency to take risks and made you 30 to 40 percent more likely to seek a divorce, although the two were not necessarily related. Said Time magazine’s issue of 25 October 2004, our DNA might even drive our religious choices and compel us “to seek a higher power.”

As for shyness, where genes might account for 50 percent of the experience, researchers were even able to point to specific genes: shy people were coming up “short” in their strands of DRD4 and 5-HTTLPR. And just a few years ago, psychologist Jerome Kagen suggested that fair-skinned, blue-eyed types had it worse, although a later study suggested that was only fair-skinned, blue-eyed males.

But, for a quick clarification, personality traits rise from a mixture of environment and genetic influences, with genes typically weighing in at 40 to 50 percent on the influence scale. And those would be genes—plural—as in many. There is no one gene/one personality trait relationship.

Still, researchers have found genetic influences for assertiveness, extroversion, anxiety, optimism, pessimism, thrill-seeking, sociability, intelligence, and career choice. A late 1990s study found that genes may even affect your attitude toward reading books or roller coaster rides. Many of these claims come from studies of twins separated at birth; and most studies estimate the “heritability” of behavioral traits to be about 50 percent.

So did my friend Catherine inherit her opinionated nature from the great-great-grandfather people compare her to? Is Ana’s generosity actually a gift from her open-handed grandmother (a team of scientists claimed to have found an “altruism” gene just last year). Is my tendency for reticence passed down from some shirt-tail cousin a century and a half ago?

Actually, the answer probably lies between “possibly” and “no.” Dr. Lindon J. Eaves, Director of the Virginia Institute for Psychiatric and Behavioral Genetics, points out that genetic influence diminishes exponentially with each generation. Say a parent influences a child’s personality by 0.2 on a scale of 0 to 1. A grandfather’s genetic influence is going to be 0.22 (or .04), a great-grandfather’s will be 0.23 (or .008) and so on. This doesn’t mean that traits aren’t passed down, but influence from a particular source quickly becomes diluted.

Likewise, all personality and behavior traits result from a mix of nature and nurture—and neither is a lock. My tendency towards thrift (is there a cheapskate gene?) is in some measure learned from my parents, who learned it from theirs. But the trait is not ubiquitous in the family. We’re probably split right about down the middle: spendthrifts on one side, tightfists on the other.

When it comes to human behavior, biology is not destiny. One thing that makes us human is our power to choose how we act. At the mere thought of going to a dinner party at a neighbor’s house, my heart rate may go up and my palms may get sweaty, but any psychologist can tell you, nervous or not, I can still elect to march up the walk and ring the bell.

So what accounts for the strange connections we discover between ourselves and our ancestors, particularly ones whom we have never met? Nature? Sure. The genes are there, interacting, making proteins that affect our responses to the world around us. Nurture, too—some things we do because we were raised that way. And it may be best to throw in a little chance—we’re all human, after all. But Dr. Eaves makes
another point:

“The way people describe their family history is the way they see themselves,” he says. “What we look for is very much conditioned by who we are.” So when people tell Catherine she’s just like her great-great-grandfather, her most powerful link to him may stem from the identity she has forged and the mythologies she and her family have built. Some of the strongest and most inexplicable bonds we have in life are those we choose to make—marriages, children, friendships. The things we find in common with other people are just more of the bonds we create that continually remind us we’re family.

Paul Rawlins is actually a relatively sociable, thrifty, blue-eyed writer and editor from