If identical twins are more similar to each other with respect to an ailment than fraternal twins are, then vulnerability to the disease must be rooted at least in part in heredity.

如果同卵双胞胎彼此在疾病方面比异卵双胞胎更相似，那么这种疾病的易感性至少在一定程度上是由遗传造成的。

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The scientists made this conclusion based on the fact that identical twins performed much more similarly than fraternal twins.

同卵双生双胞胎比以卵双生双胞胎的心智状况更为接近，科学家据此得出上述结论。

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The study found that the likelihood of both twins being affected by autism was higher among identical than fraternal twins.

该项研究发现，同卵双胞胎的两个双胞胎儿都患有自闭症的可能性比异卵双胞胎的大。

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This means that behavioural traits with a large genetic component are more likely to be shared by identical twins than fraternal twins.

ECONOMIST: Evidence that psychopaths are born, not made

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

Conversely, those traits with a large environmental component will be shared by identical and fraternal twins in equal measure.

ECONOMIST: Evidence that psychopaths are born, not made