A genome-wide association study (GWAS) tests whether each of several million sites in the human genome is correlated with a trait of interest. For a number of reasons, including replication of GWAS results within families, we can be confident that significant correlations reflect in part the causal effects of DNA-level variation on the studied trait. This level of causal inference, much stronger than in most observational studies, enables some far-reaching conclusions about the antecedents and structure of human intelligence. We discuss some of these conclusions regarding whether brain size affects intelligence and the long-debated issue of how different intelligence tests are related to each other.

中文翻译：

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用遗传方法研究智力的三个有前途的方向

全基因组关联研究 （GWAS） 测试人类基因组中数百万个位点中的每一个位点是否与感兴趣的性状相关。由于多种原因，包括 GWAS 结果在家族内的复制，我们可以确信显着相关性部分反映了 DNA 水平变异对所研究性状的因果影响。这种水平的因果推理比大多数观察性研究要强得多，可以得出关于人类智能的前因和结构的一些深远的结论。我们讨论了其中一些关于大脑大小是否会影响智力的结论，以及长期争论的关于不同智力测试如何相互关联的问题。