By Robin SmithIn his 2008 bestseller Outliers, Malcolm Gladwell argued anecdotally that when it came to success, intelligence isn’t everything. A study published this month in the journal PNAS found just that — by looking at the heritability of academic performance of teenagers on set of British standardized tests.By looking at 13,000 twins identical and fraternal twins aged 16, the study found that 62 percent of the variability of test scores could be explained by genetics. The authors found that achievement was highly correlated with intelligence, but almost as important were other characteristics such as self-belief, personality, well-being, perception of the school environment, and behavior problems. However, all of these characteristics were to some extent influenced by genetics. So what are these genetic factors? So far, only a handful of large-scale studies have identified factors affecting academic achievement.A 2013 study published in ScienceExpress identified a SNP (rs9320913) that was associated with whether or not a person had attained a college diploma, and another two (rs11584700, rs4851266) that were associated with “EduYears” — the number of years of schooling a person had. Although these variants confer modest effects — the strongest one is associated with the equivalent to about a month of schooling difference per copy of the mutation — the identification of new parts of the genome that correlate with academic achievement is a promising future direction for research.Scientists at 23andMe were interested to see if these associations held true with our customers. In a study published this month in the journal Psychological Sciences, they showed that they were. Replication studies are vitally important for confirming that the results of one study apply to different groups of people and are not due to confounding factors.