Bioethics Blogs

Bad news for “intelligence-genes”

Intelligence and its heritability has been a popular topic in scientific communities and public discussions for long. Recent findings give new insight to the debate: one of the largest studies on genetic influence to intelligence and other behavioral traits turned up inconclusive findings, as Nature News reports in a recent article “Smart genes” prove elusive.

Existing literature on candidate gene associations is rich in studies that have been unable to replicate and findings have been based on “wishful thinking and shoddy statistics”. According to an editorial in Behavior Genetics,

it now seems likely that many of the published findings of the last decade are wrong or misleading and have not contributed to real advances in knowledge.

The journal declares it will tighten its publication policy for candidate gene association studies of complex traits: they now recommend direct replication analysis prior publication and rigorous testing of statistical models. By this, they wish to decrease publication of findings brought by mere chance or other kinds of biases.

Especially twin and family studies, which repeatedly have reported a genetic basis for intelligence and behavior, are subjected to critique. The challenge is these studies is the assumption that genetic and environmental effects could be separated, but the case is not so simple.

In contrast to the criticized studies on “candidate genes”, new studies operate with genome-wide association (GWAS) scans of single nucleotide polymorphisms (SNPs) and large samples of persons – the quoted studies included more than 100,000 participants. The GWAS studies to date have not found genome-wide significant SNPs in social-science genetics that replicate consistently, and researchers predict that most reported genetic associations with general intelligence are probably false positives.

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.