For the study, first grade school children in Winterthur in northern Switzerland underwent regular tests to measure their strength, coordination and agility.
After four years of following their development, the ETH's Institute for Movement Sciences and Sport cross-referenced the data with information about the origin of their parents, their native language and their religion.
Results showed that children with no religious background tend to be the most skilful athletes. These are followed by Protestants and Catholics. At the opposite end of the spectrum are Muslim children, who performed well below the average, especially girls.
According to the director of the school, Stefan Fritschi, Muslim girls are often reluctant to participate in sports that involve bodily contact with other children. Similarly, swimming lessons are problematic, as Muslim families try to remove their daughters from the classes.
Language also plays a role. German-speaking students show much better results than children with other first languages, such as Bosnian and Albanian.
"The differences are considerable, but not really surprising,” the head of the study, Andreas Krebs, told newspaper Tages Anzeiger. “Parents from south-eastern Europe often have a different level of access to sports. There's also a different beauty ideal,” he added.
However, for Krebs, the most important differences relate to the social status of the family. The richer and more educated they are, the better their children do in sports tests.