Dealing with difficult parents can be immensely stressful. Especially the ones who always seem to know better than you. The fact is that while you’ve been trained in the latest theories of child development, most parents have only a partial understanding of child psychology, and much of that has been gleaned from the shelves of their local bookshop.

Advice books on parenting are now the bestsellers of the self-help sector, according to a survey published in the journal Family Relations in January.

But how reliable are these books, given that most are not written by child psychiatrists but by non-specialist “name” authors who have a good record when it comes to clocking up sales?

Dr Laura Schlessinger and Dr John Gray have penned the biggest-selling parental advice books of recent years. Gray’s Children are from Heaven recently spent 12 weeks in the New York Times bestseller list; Schlessinger’s Parenthood by Proxy made the list for four weeks. According to Schlessinger’s website, her syndicated radio show is on about 300 stations with 12 million listeners. Gray’s syndicated newspaper column reaches 30 million readers, and his Men are from Mars, Women are from Venus has sold more than 30 million copies in 40 languages.

However, Gray, a family therapist, gained his PhD from Columbia Pacific University, California, an unaccredited correspondence school that was shut down in the late 1990s by the state attorney general. Academic credentials are, of course, not a prerequisite for imparting sensible advice on how to bring up children. But child psychologists are increasingly concerned at the impact that populist gurus are having on children’s development.

Professor Toni Zimmerman of Colorado State University has led a team of family specialists who have investigated self-help books for mothers. They have found that a recurring theme in Schlessinger’s books is her denigration of working mothers: they are selfish and greedy people who are damaging their children by placing them in childcare. Women are told that if they want a career, they should not have children.

Yet most research into this issue concludes that neither the mother-child relationship nor the quality of parenting is adversely affected by a mother working. Children who receive good quality childcare do as well, or sometimes better, than children receiving full-time maternal care. The relationship between childcare and outcomes for children is much more complex than Schlessinger claims.

In Children are from Heaven, Gray does attempt to invoke science to support his thesis that boys and girls require quite different parenting techniques. He argues that girls need to feel supported, cared for, understood and helped. In contrast, he suggests that boys require independence, confidence, space, and opportunities to try to solve their own problems. But all children, regardless of gender, require all of these traits to be successful individuals.

Professor Zimmerman and her colleagues describe the advice in these books as “irrelevant at best and harmful at worst”. They point out that many readers might be unaware that much of the advice they are given is contradicted by empirical literature on family well-being. So next time you are wrestling with a parent who doesn’t seem to know the basics about their own children, remember under whose influence they may have fallen.

Professor Raj Persaud is a consultant psychiatrist at the Bethlem Royal and Maudsley hospitals in London. His latest book is The Motivated Mind (Bantam Press, pound;12.99). Email: rajpersaud@tes.co.uk