Many scientists once believed that physical similarities between identical twins are genetic, while their personalities, intelligence and other differences between them are an effect of their environment.

许多科学家曾经认为，同卵双胞胎在外貌上的相似是由基因决定的，而他们之间的性格、智力和其他差异则是受到环境的影响。

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In contrast to the blaze of sunlight outside, the inner light had a soporific effect, especially on the twins.

与户外灿烂的阳光相比，室内的光线有种催眠效果，这对双胞胎尤其明显。

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But when they looked at how the identical twins behaved over the course of the 12-year study period, they found marriage did have an active effect.

他们对一对同卵孪生兄弟进行为期12年跟踪研究发现，婚姻是对他们行为确实有重要影响。

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They used the classic trick of neutralising the effect of upbringing and exposing that of genetics by comparing identical twins (who share all their genes) with fraternal twins (who share half).

ECONOMIST: Evolution

Now that they're working together as The Gutter Twins, however, they've forged a new hammer of the gods for themselves, to enthralling effect.

NPR: 'Idle Hands' and the Hammer of the Gods