If a kid is turning out to be a couch potato when it should be playing all around, the reason may well be that the physical activity levels of the mother is also low, shows research.
Young children are not 'just naturally active' and that parents have an important role to play in the development of healthy activity habits early on in life.
"We saw a direct, positive association between physical activity in children and their mothers - the more activity a mother did, the more active her child," said Kathryn Hesketh of University College London.
The research drew on data obtained from 554 women and their four-year-old children.
Of the 554 mothers whose data was analysed in the Cambridge University-led study, many were working and many of the children attended day-care facilities - factors that influenced activity levels of both mothers and children, as well as the association between the two.
Other potential influences on maternal activity examined in the study included maternal education, whether the child had siblings, and whether his or her father was present at home.
Both mothers and youngsters were fitted with Actiheart monitors (combined accelerometer and heart rate monitor) to record with a high degree of accuracy their physical activity levels for up to a week with a high degree of accuracy.
"We used an activity monitor that was attached to participants and worn continuously, even during sleep and water-based activity," said Esther van Sluijs from the University of Cambridge.
"This approach allowed us to capture accurately both mothers' and children's physical activity levels for the whole of the measurement period, matching hour for hour maternal-child activity levels."
The study, which appeared in the journal Pediatrics, suggests that policies to improve children's health should be directed to whole families and seek to engage mothers in particular.