Losing the genetic lottery

Scimex: So, it turns out that we really can lose the genetic lottery. An international study, including Australians, found those of us who have inherited more identical gene copies from our parents are more likely to be short in stature, short of breath, lacking in intelligence, and to be educational underachievers. The researchers say that the effect is equivalent to the children of first cousins being 1.2 cm shorter and having 10 months' less education than the general population. An analysis of over 350,000 individuals reveals a small but measurable association between genome-wide homozygosity and four complex traits: height, lung function, cognitive ability and educational attainment. The findings are published in Nature this week.


All humans are at least distantly related to each other. Genomic techniques now allow for that degree of relatedness of someone's parents to be quantified using a measure called genome-wide homozygosity. Jim Wilson and colleagues studied stretches of the genome where identical sequences have been inherited from both parents, then looked for links between these 'runs of homozygosity' and various traits related to public health. Increased levels of homozygosity correlate negatively with height, lung function, cognitive ability and educational attainment, the authors found. The effect is equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months' less education. In contrast to previous, much smaller studies, blood pressure, low density lipoprotein (LDL) cholesterol levels and various other cardio-metabolic traits were not found to be linked to parental relatedness.

Similar effects were found across large populations spanning over four continents, suggesting that factors such as height and cognitive ability may have been positively selected in human history, whilst many important risk factors related to complex disease have not.