Though the prevailing Father's Day question is what to get Dad, a new study suggests the more pressing issue is what dads can give in return.

In a long-term analysis of 36 international studies of nearly 11,000 parents and children, researchers have found that a father's love contributes as much - and sometimes more - to a child's development as that of a mother, while perceived rejection creates a larger ripple on personality than any other type of experience.

The power of paternal rejection or acceptance is especially strong in cases where the father is seen by his child as having heightened prestige in the family, as this tends to boost his influence.

"In our half-century of international research, we've not found any other class of experience that has as strong and consistent an effect on personality as does the experience of rejection - especially by parents in childhood," says co-author Ronald Rohner, whose study appears in the journal Personality and Social Psychology Review.

"In many instances, fathers are as important developmentally as mothers. In some instances, they turn out to be even more important developmentally than mothers. And what we find extraordinary is that, sometimes, a mother's influence drops out altogether."

Across decades of studies, with a total 10,943 adults and children, perceived paternal acceptance was linked to less hostility; independence; healthy self-esteem; feelings of adequacy; emotional stability and responsiveness; and a positive world view.

By contrast, perceived paternal rejection was significantly linked to problems with anger or aggression; lower self-esteem; feelings of inadequacy; emotional instability and unresponsiveness; and a dim world view.

"There's a very consistent worldwide effect of impaired psychological adjustment wherever kids perceive themselves to be rejected by Mom or Dad. And that effect shows up more significantly for dads than for moms," says Rohner, professor emeritus of family studies at the University of Connecticut.

To wit, a father's rejection more strongly predicted four classes of child behaviour than a mother's: behavioural problems, substance abuse, depression and overall maladjustment.

A father's love, meanwhile, more strongly predicted satisfaction and wellbeing, and acted as a better buffer against substance abuse and depression.

"We've assumed for years that all kids need for normal, healthy development is a loving relationship with Mom, and that dads are primarily there as financial supports for the family," says Rohner. "We now see how fundamentally wrong that is."

Gary Direnfeld, a social worker from Dundas, Ont., said he hopes the study will help quell the tendency to treat mothers as both sole hero and villain in a child's life - alternating between bashing and enshrining them, depending on the youngster's behaviour.

"We all want well-rounded children. Well, children are a product of two parents and both should be meaningfully involved wherever possible," says Direnfeld, an expert on family life.