According to a new study, children are more likely to become taller, smarter and better educated when their parents share fewer genes; that is, the more distantly related the latter are, the greater is the chance of the offspring to have the qualities mentioned. The findings have been published in the journal Nature.
Genetic diversity has long since been hailed as one of the factors ensuring the survival of species on the planet. Conversely, scientists believe that closely related parents entail greater risks for their children to have genetic defects. However, no study actually hinted at whether the opposite – that children of distantly related parents have more advantages pertaining to genetic traits like height – was also true.
The study is one of the largest researches that delve into the topic of genetic diversity. It takes into consideration 110 papers on genetics that account for over 350,000 individuals from the 4 continents, Africa, Asia, Europe and North America. The findings of the new study suggests that higher average in height and intelligence all across the globe might result from the coupling of individuals coming from different genetic backgrounds.
The genetic information of 354,224 people from 102 groups was analysed. Cases of homozygosity, whereby offspring obtain the same DNA copies from the two parents (mostly because the latter are closely related), was identified. Homozygosity is often associated with the expression of adverse, recessive traits.
When the researchers compared this result with 16 traits of public health importance, they found that four of these – height, lung capacity, cognitive ability and level of education – could be linked with genetic diversity.
For instance, children born from unions between cousins were on average 1.2 cm shorter. They also had 10 months’ less education than their counterparts who came from genetically diverse parents.
“Most people would believe a diverse gene-pool is a good thing, but the discovery that height is associated with diversity wouldn’t have been foreseen,” said one of the researchers, Nathan Richardson from the UK Medical Research Council, in a statement to The Guardian.
However, the researchers yet have to establish the effect other factors like environmental ones have on the trait. Still, Oldfield explains that their findings might explain why humans are becoming smarter and taller:-
“These results could also go some way to explaining the ‘Flynn Effect’ – the increase in intelligence from one generation to the next first documented in the 20th century.
“While socio-economic factors such as increased schooling and better nutrition are generally seen as primary drivers, increased genetic diversity could also play a small role. The increases in intelligence [from the Flynn Effect] are too big to be explained by our results alone, but they might be a contributor.”