If you feel you have a closer relationship with your granny on your mother's side than the one on your father's side, it is no surprise to researchers at the universities of Newcastle and Antwerp. Based on studies in the Netherlands, they claim that maternal grandparents are likely to make greater efforts to maintain frequent contact with their grandchildren than paternal grandparents.

They speculate that psychological mechanisms related to human evolution are involved: women, because of maternity, are always sure of their relationship to their sons or daughters, whereas men can never be wholly certain they are their children's biological fathers, the researchers suggest.

Furthermore, maternal grandparents are always more certain than paternal grandparents that a grandchild is related to them: "Thus maternal grandparents, especially maternal grandmothers, may go the extra mile to visit their grandchildren."

The study, carried out by Thomas Pollet and his colleagues, found that for grandparents living within 30km of their grandchildren, more than 30 per cent of maternal grandmothers and 25 per cent of maternal grandfathers had contact daily or a few times a week. In contrast, only 15 per cent of paternal grandparents had the same level of contact.

Mr Pollet said: "Even in families where there has been divorce, we found consistent differences. Grandparents on your mother's side make the extra effort."