THE belief that children and money will bring people happiness is one of life's abiding illusions, a Sydney conference attended by 2000 seekers of happiness was told yesterday.

The scientific evidence shows people are very bad at predicting what will make them happy, said Daniel Gilbert, a professor of psychology at Harvard University and the author of the book Stumbling On Happiness. He said people's happiness goes into steep decline after they have children, and never recovers its old level until the children leave home. As a source of pleasure, playing with one's offspring rates just above doing housework but below talking with friends, eating, or watching TV, research has shown.

Yet people invest so much time and money in their children, and focus on the fleeting moments of joy they bring, rather than on the long periods of boredom and irritation, that most continue to believe children will bring them happiness, Professor Gilbert said.