Do names matter?
To a remarkable degree, they do. Though we don't choose them, our names are badges bearing information about our class, education level, and ethnic origin — or at least those of our parents. Scientific studies have shown that the world makes different assumptions about a boy named Tyrone than it does about one named Philip, and while those assumptions are often wrong, they can have a considerable influence on the course of a life. A name can even exert unconscious influence over a person's own choices. Some scientific researchers contend that there are disproportionately large numbers of dentists named Dennis and lawyers named Lauren, and that it's not purely an accident that Dr. Douglas Hart of Scarsdale, N.Y., chose cardiology or that the Greathouse family of West Virginia runs a real-estate firm. To some degree, this has always been true: The Romans had the expression nomen est omen, or "name is destiny."

Has the way we name kids changed?
In this country it has. Most families used to give boys names chosen from a repertoire established within a family over generations, and while that was less true for girls, there was a relatively finite range of acceptable names, largely limited to those of saints. But in recent decades, the number of names in circulation has exploded. In 1912, when the most popular names in America were John and Mary, parents of 80 percent of American babies chose from among the 200 most common names. Today less than half of girls and about 60 percent of boys are accorded a top-200 name. One study found that 30 percent of African-American girls born in California during the 1990s were given names they shared with no one else born in the state in the same year.

What influences those choices?
The simple answer is taste, but taste is a complex thing. Names come into and fall out of fashion much as clothing styles, musical genres, and haircuts do. None of the top five girls' names from 1912 — Mary, Helen, Dorothy, Margaret, and Ruth — ranked in the top 40 in 2010, when the leaders were Emma, Olivia, Sophia, Isabella, and Ava. The name Wendy surged after the release of the movie and musical Peter Pan in the early 1950s, and Brittany took off in the 1990s with the career of pop star Britney Spears. The popularity of the names Isabella, Jacob, and Cullen in recent years has been linked to characters with those names in Stephenie Meyer's Twilight series of vampire novels.

Is it good to have a popular name?
In situations where the name is all that is known, people with common first names fare better than those with unique ones. Studies have found that a résumé submitted under a name perceived as African-American, such as Lakesia Washington, gets less attention from potential employers than the identical résumé bearing a more "Caucasian" name, like Mary Ann Roberts. A recent Australian study found that people tend to have better impressions of co-workers and political candidates whose names they can pronounce easily. Nonetheless, in this era of individual self-expression, many parents view commonplace names like Thomas or Jane as boring and uncreative. "For some parents, picking out a baby name is like curating the perfect bookshelf or outfit," said writer Nina Shen Rastogi in "It should telegraph refinement without snobbishness, exclusivity without gaucheness, uniqueness without déclassé wackiness." That's a fine line to walk: Aiden, one of the most popular boy's names in the U.S. over the last seven years, has now lost the exclusivity that made it attractive to many parents.

How do we react to our own names?
Research indicates that people are unconsciously drawn to things, people, and places that sound like their own names. Psychologists call this phenomenon "implicit egotism." The Swiss psychiatrist Carl Jung noted that his colleague Sigmund Freud (German for "joy") advocated the pleasure principle, Alfred Adler ("eagle") the will to power, and he himself ("young") the "idea of rebirth." A controversial 2007 study cited implicit egotism as the reason why students whose names began with a C or a D had lower grade point averages than those with names beginning with an A or a B; students gravitate to grades, the study argued, that reflect their own beloved initials.

So are our names our destiny?
They undoubtedly have influence, but "destiny" is too strong a word. "Names only have a significant influence when that is the only thing you know about the person," says psychologist Dr. Martin Ford of George Mason University. "Add a picture, and the impact of the name recedes. Add information about personality, motivation, and ability, and the impact of the name shrinks to minimal significance." Condoleezza Rice's name might have held her back, but she was so smart, talented, and driven that she became secretary of state. On the other hand, there are people like Sue Yoo of Los Angeles, who grew up with people telling her, "Oh my god, that's your name, you should totally become a lawyer." Today she's an attorney. "Psychologically," she says, her name probably "helped me decide to go in that direction."

Names of the West
Where you live has a big impact on what names you prefer for your children. In the American West, University of Michigan researcher Michael Varnum has found, parents are more likely to give their children unconventional names than residents of the Eastern seaboard are. He says that reflects the persistence of the pioneer preference for "individualistic values such as uniqueness and self-reliance." You'd think that biblical names would be more popular in conservative regions, but the reverse is true. Naming expert Laura Wattenberg says that "classic, Christian, masculine" names like Peter and Thomas are more popular in blue states, while "an androgynous pagan newcomer like Dakota" is more likely to show up in a red state. Alaska's Sarah Palin, that Western avatar of traditional values, is a perfect example of that paradox: She named her children Track, Bristol, Willow, Piper, and Trig.