Want tall, smart kids? Then travel further to find a partner

If you want to have children who are tall and smart, then be prepared to travel further to find a partner. New research has found the lower the degree of genetic similarity in a couple, the more likely it is their children will be taller and quicker thinkers.

This formula also seems to work in reverse, with shorter children more likely as parental “relatedness” increases.

People have always known that having children with a relative increases the risk of serious disorders.

But ultimately all humans are related to one another, so does a low level of “relatedness” make a difference?

Dr Jim Wilson, a research fellow at the centre for population health sciences at the University of Edinburgh, decided to try and answer this question.

He pooled together data from 102 separate studies which contained genetic information on more than 354,000 people.

The more related your parents are, the more likely you are to carry identical pairs of genes, one from father and one from mother. Wilson and colleagues used this, known as genome-wide homozygosity, as a measure of relatedness.

The researchers then looked for any link between 16 different public health traits and the level of genetic relatedness.

They found some connections. The less related the parents, the more likely the offspring were to be taller, have better cognitive ability and a higher educational attainment.

They found these offspring also had better lung function but “no evidence was seen” of a connection with high blood pressure, levels of cholesterol or other related traits. the authors said.

The process seems to work in reverse for offspring of more closely related parents. The children were often shorter, “equivalent to the offspring of first cousins being 1.2 centimetres shorter and having 10 months’ less education”, the authors said.

They published their findings on Wednesday in the journal Nature.

The researchers don't indicate how far one needs to travel to dip into a completely different gene pool.. The authors do say, however, their study "provides evidence that increased stature and cognitive function have been positively selected in human evolution".