Although the cause of hypertension is unknown in 90-95 percent of adults, primary hypertension is uncommon in children, occurring in less than 1-2 percent of hypertensive children.
Everyone can benefit when a heart-healthy lifestyle is followed, so the dietary and activity changes made for the hypertensive child will benefit the entire family.
Sorof, Jonathan M., et al. "Cardiovascular risk factors and sequelae in hypertensive children identified by referral versus school-based screening."
Some children inherit a tendency to develop hypertension, and the risk increases if both parents are hypertensive.