Want a tall child? Be sure that your spouse is born far away from your town, scientists say.
Polish researchers found that if couples were born in the same town, their children are slightly shorter on average than the kids of parents with far-flung origins.
The researchers think the reason boils down to genetics: Parents originating in very different regions likely have very different genes relative to a mother and father who both grew up in the same home town, where their own parents grew up.
That greater genetic diversity may lead to children with bodies that operate more efficiently than others. Energy saved by this efficiency could then go to growth, said study author Dariusz Danel of the Institute of Anthropology at the Polish Academy of Sciences.
“This effect is visible in children during the three analysed stages of the development period, ranging from 6 to 18 years of age,” Mr. Danel was quoted as saying by LiveScience.
According to the researchers, height is determined by a number of factors, including parents’ height and socioeconomic status, because wealthier people tend to be better nourished. Earlier studies had found conflicting evidence about whether marital distance — the distance between parents’ birthplaces — matters in how tall children get.
Mr. Danel and his colleagues, who reported their findings in the American Journal of Physical Anthropology, used a dataset of the heights of 2,675 boys and 2,603 girls in Poland, measured yearly in the children’s schools. They also collected information on their parental height and family income.
The latter two factors played an expected role in a child’s height, but the researchers also found “unambiguous” evidence that marital distance mattered, too, Mr. Danel said. Marital distance explained about 20 per cent of the variations in height among boys and 14 per cent of the variations in height among girls, he said.