WHY does it take costly research to prove that lively rough and tumble with dad helps boys grow up better adjusted?

Charlie Lewis -- a professor of development psychology at Lancaster University -- is presenting findings on father-son relationships at an Oxford seminar this week.

Apparently, boys who play-fight with their fathers are likely to be friendly, popular and easygoing at school. And those discouraged from this are more likely to become bullies or victims of bullying.

In other words, gasps, if there are physical demonstrations of affection, including boisterous play, in a warm, loving home, our children have a better chance of development.

Brilliant.