Brains alone don't make a star student. Motivation and self-confidence—what some psychologists call “self-perceived abilities” (SPAs)—are important, too. Now, psychologists report that not only IQ but SPAs as well are strongly influenced by genes. A team led by Corina Greven of the Institute of Psychiatry in London examined data from a large longitudinal study of British twins. For 1217 identical twin pairs and 1070 same-sex fraternal twin pairs, all 9 years old, the researchers compared school test scores, IQ scores, and results of a test in which the subjects ranked themselves on a five-point scale ranging from “not at all good” to “very good” at English, math, and science subjects. By comparing scores of identical twins (who share 100% of their genes) and fraternal twins (with 50%), the researchers estimated a heritability for SPAs at 51%. “Contrary to extant theories, SPAs are substantially influenced by genetic factors, … at least as much as IQ is,” they wrote online last month in Psychological Science . Heritability of IQ, which goes up with age, was estimated at .43 for the 9-year-olds. “I don't think anyone has looked at this before,” says Nicholas Martin, a twin researcher at the Queensland Institute of Medical Research in Brisbane, Australia. “It would be interesting to explore further what the roots of self-confidence are, since it seems to be semi-independent of true ability.”