Children whose parents are thinner are three times more likely to be thin than children whose parents are overweight, a new study suggests.
Researchers at the University College London recorded the height and weight of parents and up to two children in 7,000 families over a five-year period.
The analysis of body mass index (BMI) found that when both parents were at the lower half of the ideal BMI range, the chance of the child being thin was 16.2 percent, compared with 7.8 percent when both parents were in the upper half.
The researchers also found that the chance of a child being thin was just 5.3 percent when both parents were overweight and only 2.5 percent for children whose parents were obese.
The results suggest that thinness may be inherited, with children of thinner parents being likely to be genetically predisposed to a lower body weight.
"We know from other studies that children's weights are correlated with those of their parents, but previous research has tended to focus on obesity rather than the other end of the spectrum," said lead author Dr Katriina Whitaker, UCL Epidemiology and Public Health.
Professor Jane Wardle, from the same unit, added that parents are often concerned if their child is thin, but it may just be their 'skinny genes'.
"All genes have two versions, called alleles. We might think of weight-related genes as having a 'skinny' and 'curvy' allele. Thinner parents are likely to have more of the skinny alleles, increasing the chance of passing them on to their children. A child who inherits more of the skinny alleles from their parents will be naturally thinner," she added.
The study is published in current issue of the Archives of Pediatrics and Adolescent Medicine.