An increasing number of young adults are moving back into their parents' homes after they have supposedly flown the nest.

Soaring property prices, combined with unprecedented levels of relationship breakdown and greater career instability, mean that offspring aged 20 to 30 are now returning to live with their parents more often and staying longer when they get there.

Almost one in four of this age group is now living with parents, according to a study published today by the Social Market Foundation, the independent think tank. The trend has given rise to a new phenomenon the report termed "lifelong parenting". It is being bolstered by a change of attitude in young adults in which living with Mum and Dad is no longer seen as a source of ridicule. More than half of adult children living with their parents said they were perfectly happy to do so.

Although the phenomenon of lifelong parenting has significant financial implications for parents, it is also clear from the research that children who have left home are giving something back. There is little sense that children are simply pillaging their parental resources, emotional and financial, before leaving home and severing all relations. Over one in three (37%) have give, their parents financial help.

"One of the reasons we choose dogs as pets is that there appears to be in their attachment a capacity for an altruistic love, a willingness to please another without outward reward," Fogle writes. "But we also choose them because we are helplessly programmed to do so."

In a recent interview, he expanded on the thought: "Humans are programmed for lifelong parenting. And pets don't hesitate to take advantage of this need in us.