Parents 'not to blame'
They are not to blame for their children's delinquency. In fact, fathers and mothers will be alarmed to hear they have little - if any - effect on the character of their offspring.
Aside from genetic factors, it is peers, not parents who are the key to the way that children grow up.
This brave thesis has been put forward by a New Jersey grandmother, Judith Rich Harris, whose book, The Nurture Assumption, is to be published in the autumn.
She has no PhD or professorial title and worked on her controversial theory in her sitting room. All the same, Mrs Rich Harris has received much distinguished applause and is about to receive a prestigious award from the American Psychological Association.
Her big idea - that children copy other children rather than the example of their parents - upsets most of the conventional wisdom which has placed the responsibility for a child's character on a mixture of genetics and home influence.
While accepting the role of genetics, Mrs Harris argues that the emphasis on parents is mistaken. Despite years of looking, no one, she says, has been able to pin down the relationship between the example set by individual parents and the effect on their children.
She points, for example, to studies of twins separated at birth. If the example of parents is crucially important to children, then those who spend many hours a day with their parents should be different from those who spend only two hours a day with them. But the evidence shows no such difference.
Nor does it appear to matter whether or not the parents are happy, sad, educated or illiterate.
Instead, she says, it is the world outside the home that proves important. Mrs Rich Harris instances studies showing that living in a troubled area is more likely to produce delinquency than living in a troubled family.
Even the loss of parents through divorce or death, she concludes, is less important than the consequent disruption of the child's peer relationships through sudden poverty or moving house.
"Kids are not that fragile," she writes. "They are tougher than you think. They have to be because the world out there does not handle them with kid gloves."
In a recent interview for The New Yorker, she says, "I want to tell parents that it's all right.
"A lot of people who could be contributing children to our society are reluctant to do it because they feel that it requires such a huge commitment.
"You can have a kid without having to devote your entire life - your entire emotional expenditure - to this child for the next 20 years."