Parents who exert too much psychological control over their children leave them unhappy and dependent later in life.
A study of thousands of Britons from their teens to their sixties found that adults whose parents intruded on their privacy in childhood or encouraged dependence were unhappier and had lower mental well-being.
The life-long negative impact was similar to that experienced by people who have suffered a bereavement, experts from University College London said.
The news will rekindle the debate over so-called helicopter parents and tiger mothers who take an over-protective or excessive interest in their children's lives, but often fail to show warmth or care.
Participants were monitored from 13 to 15 by teachers, and interviewed in their thirties, forties and sixties.