Smart kids tend on balance to do well in school. That may seem obvious, but there are a lot of exceptions to that rule. Some kids with high IQs don’t ever become academic superstars, while less gifted kids often shine. Why would this be?

Psychologists have focused on things like self-esteem and confidence—how good kids think they are—to explain these outcomes. And the assumption has always been that such psychological traits are shaped mostly by parenting—by parents’ beliefs and expectations and modeling. But surprisingly this idea had never been scientifically tested.

Until now. Behavioral geneticist Corina Greven of King’s College London and her colleagues decided to do the first rigorous analysis of the heritability of confidence—and its relationship to IQ and performance. To do so, they studied more than 3700 pairs of twins, both identical and fraternal twins, from age seven to ten. Comparing genetically identical twins to non-identical siblings allows scientists to sort out the relative contributions of genes and environment, and when they did this they came up with surprising but unmistakable findings.

Contrary of accepted wisdom, the researchers found (and report in the June issue of Psychological Science) that kids’ confidence is heavily influenced by heredity—at least as much as IQ is. Indeed, as-yet-unidentified confidence genes appear to influence school performance independent of IQ genes, with shared environment having only a negligible influence.

The fact that confidence is heritable does not mean it is unchanging, of course. Siblings share a lot of influences living in basically the same home and community, but there are always worldly influences pulling them apart. A genetic legacy of self-confidence merely opens up many possible futures.

聪明的孩子通常在学校的各方面表现良好。那些看起来似乎是显而易见的，但对于这个规律有许多例外。一些智商高的的孩子从来没成为过学习尖子生，然而不那么有天赋的孩子却经常出色。为什么出现这种情况呢？

心理学家曾经着重于研究自尊和自信，通过孩子觉得他们怎么样的问题来解释这些结果。而且这个假设总是：这种心理上的性状大多是由家庭教育，由家长的信仰,期望和树立的榜样的影响而形成的。但令人吃惊的是这个想法从未被科学的证实过。

直到现在，伦敦大学国王学院的行为遗传学家Corina Greven和她的的同事们决定做第一个严格的遗传信心的分析，以及它和智商，成绩的关系。为了做这些，他们研究了超过3700对双胞胎，清一色的兄弟双胞胎，年龄在7到10岁之间。通过比较基因完全相同的双胞胎与不相同的兄弟姐妹，科学家理清了基因的作用和环境的关系，当他们做这些时，他们想出了令人吃惊但无误的研究结果。

同公认的智慧相反，研究者发现（并且发表在六月的心理科学杂志上）孩子的信心至少和智商一样严重的被遗传所影响，实际上，还未被识别的自信基因看起来对成绩的影响独立于智力基因，共同的成长环境只有微不足道的影响。

信心是遗传的这个事实并不意味着它是不可改变的，当然，兄弟姐妹住在基本上同一个家同一个社区，受许多同样的影响，但有些世俗的影响会把他们区分开。自信基因的传承只是开辟了许多可能的未来。