People who are shorter than average are more likely to have lower IQs than those who are taller, researchers in Scotland and England said. A joint study involving Edinburgh University, Aberdeen University and University College London, said the findings were based on data compiled on thousands of people recruited over a five-year period for the Scottish Family Health Study. Intelligence was determined by a series of tests. Unlike previous studies, the researchers analyzed DNA markers in more than 6,800 unrelated people from 2006 to 2011. The study, submitted to the Behaviour Genetics journal, found 70 percent of the link between height and IQ could be explained by genetics, but the remaining 30 percent was inked to environmental factors. "We tested whether DNA-based genetic similarities among people related to their similarities in height and intelligence. Previous studies have used twin or family data to examine similarities between height and intelligence, whereas ours was the first to examine this using DNA markers in unrelated people," Riccardo Marioni of Edinburgh University's Institute of Genetics and Molecular Medicine told the Scotsman.com. "We found a moderate and statistically significant genetic correlation between height and general intelligence."