Scientists have investigated this question for more than a century, and the answer is clear: the differences between people on intelligence tests are substantially the result of genetic differences.
科学家们已经研究了一个多世纪的这个问题，答案很明确：人们在智力测试中的差异主要是基因差异的结果。
But let's unpack that sentence. We are talking about average differences among people and not about individuals. Any one person's intelligence might be blown off course from its genetic potential by, for example, an illness in childhood. By genetic, we mean differences passed from one generation to the next via DNA. But we all share 99.5 percent of our three billion DNA base pairs, so only 15 million DNA differences separate us genetically. And we should note that intelligence tests include diverse examinations of cognitive ability and skills learned in school. Intelligence, more appropriately called general cognitive ability, reflects someone's performance across a broad range of varying tests.
但让我们来解读这句话。我们谈论的是人与人之间的平均差异，而不是个体。任何一个人的智力都可能因为童年时期的疾病等原因偏离其遗传潜力。在这里，遗传指的是通过 DNA 代代相传的差异。但我们共享三十亿 DNA 碱基对的 99.5％，因此只有 1500 万个 DNA 差异在遗传上分隔我们。我们应该注意，智力测试包括对认知能力和在学校学到的技能的多样化考察。智力，更恰当地称为一般认知能力，反映了某人在各种不同测试中的表现。
Genes make a substantial difference, but they are not the whole story. They account for about half of all differences in intelligence among people, so half is not caused by genetic differences, which provides strong support for the importance of environmental factors. This estimate of 50 percent reflects the results of twin, adoption and DNA studies. From them, we know, for example, that later in life, children adopted away from their biological parents at birth are just as similar to their biological parents as are children reared by their biological parents. Similarly, we know that adoptive parents and their adopted children do not typically resemble one another in intelligence.
基因起着重要作用，但并非全部。它们解释了人类智力差异的大约一半，因此一半是由环境因素引起的，这为环境因素的重要性提供了有力支持。这一估计的 50％反映了双胞胎、领养和 DNA 研究的结果。通过它们，我们知道，例如，生活中晚些时候，出生时被送养的孩子与生物父母一样类似于他们的生物父母，而被生物父母抚养的孩子。同样，我们知道，领养父母和他们的被领养子女在智力上通常不相似。
Researchers are now looking for the genes that contribute to intelligence. In the past few years we have learned that many, perhaps thousands, of genes of small effect are involved. Recent studies of hundreds of thousands of individuals have found genes that explain about 5 percent of the differences among people in intelligence. This is a good start, but it is still a long way from 50 percent.
研究人员现在正在寻找与智力有关的基因。在过去几年中，我们已经了解到许多，也许成千上万个影响较小的基因参与其中。最近对数十万人的研究发现，有些基因可以解释人们智力差异中约 5％的部分。这是一个良好的开端，但距离 50％还有很长的路要走。
Another particularly interesting recent finding is that the genetic influence on measured intelligence appears to increase over time, from about 20 percent in infancy to 40 percent in childhood to 60 percent in adulthood. One possible explanation may be that children seek experiences that correlate with, and so fully develop, their genetic propensities.
最近一个特别有趣的发现是，遗传对智力测量的影响似乎随着时间的推移而增加，从婴儿时期的约 20％增加到儿童时期的 40％，再增加到成年时期的 60％。一个可能的解释是，儿童寻求与其遗传倾向相关的经验，从而充分发展他们的遗传倾向。
The ability to predict cognitive potential from DNA could prove tremendously useful. Scientists might use DNA to try to map out the developmental pathways linking genes, intelligence, the brain and the mind. In terms of practical implications, we have known for decades about hundreds of rare single-gene and chromosomal disorders, such as Down syndrome, that result in intellectual disability. Finding additional genes that contribute to intellectual disability could help us perhaps prevent or at least ameliorate these cognitive challenges.
从 DNA 预测认知潜力的能力可能会被证明非常有用。科学家们可能会利用 DNA 来尝试绘制连接基因、智力、大脑和思维的发展途径。就实际影响而言，几十年来我们已经知道了数百种罕见的单基因和染色体异常，比如唐氏综合征，导致智力障碍。找到更多导致智力障碍的基因可能有助于我们预防或至少缓解这些认知挑战。
Question submitted by Rowena Kong, via e-mail
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