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.

    聰明的孩子通常在學校的各方面表現良好。那些看起來似乎是顯而易見的，但對于這個規律有許多例外。一些智商高的的孩子從來沒成為過學習尖子生，然而不那么有天賦的孩子卻經常出色。為什么出現這種情況呢？

    心理學家曾經著重于研究自尊和自信，通過孩子覺得他們怎么樣的問題來解釋這些結果。而且這個假設總是：這種心理上的性狀大多是由家庭教育，由家長的信仰，期望和樹立的榜樣的影響而形成的。但令人吃驚的是這個想法從未被科學的證實過。

    直到現在，倫敦大學國王學院的行為遺傳學家Corina Greven和她的的同事們決定做第一個嚴格的遺傳信心的分析，以及它和智商，成績的關系。為了做這些，他們研究了超過3700對雙胞胎，清一色的兄弟雙胞胎，年齡在7到10歲之間。通過比較基因完全相同的雙胞胎與不相同的兄弟姐妹，科學家理清了基因的作用和環境的關系，當他們做這些時，他們想出了令人吃驚但無誤的研究結果。

    同公認的智慧相反，研究者發現（并且發表在六月的心理科學雜志上）孩子的信心至少和智商一樣嚴重的被遺傳所影響，實際上，還未被識別的自信基因看起來對成績的影響獨立于智力基因，共同的成長環境只有微不足道的影響。

    信心是遺傳的這個事實并不意味著它是不可改變的，當然，兄弟姐妹住在基本上同一個家同一個社區，受許多同樣的影響，但有些世俗的影響會把他們區分開。自信基因的傳承只是開辟了許多可能的未來。