The secret to a happy marriage?

What, exactly, constitutes housework?

For a study entitled "Fifty years of change updated: Cross-national gender convergence in housework" and published in the Demographic Research journal, the authors - researchers from the University of Oxford - define it as the "most disliked, routine, and traditionally feminine-defined housework activities of laundry and cleaning, food preparation, and cooking."

Traditionally "masculine or gender-neutral chores," including home maintenance, car repairs or shopping, were disregarded for the purposes of the survey.

Gender equality: the gap is narrowing

The authors found "a general movement in the direction of greater gender equality" in data covering five decades"despite short-term stalls, slow-downs, and even reverses."

But they also noted "significant country differences."

The study covers the years from 1961 to 2011, and is based on answers from men and women in 19 countries, from Australia to Israel.

In countries where men and women’s time in housework was already more equal - like the Scandinavian countries, the US, Canada and Australia - the researchers note a slowing of gender convergence after the late 1980s.

Ingrained stereotypes

Women from Italy and Spain continued to do far more housework than women in other countries until the end of the first decade of the 21st century, with Italian men in particular "consistently doing less housework than men from other countries."

According to the data, Italian women still spent four hours and 20 minutes on household chores per day in 1980 - 15 times as much as their husbands, who with invested all of 17 minutes.

In Germany, women spend three times more time cooking and cleaning than men - in the 1960s, they spent 14 times as long as their husbands scouring the house and cooking the meals. In the US, the figure dropped from women doing more than seven times as much housework in 1965 to more than twice as much in 2010.

The gender division of housework is important for a couple's well-being, the study's authors argue, adding that disagreements over housework are among the "major sources of marital conflict."

Cleaning, cooking, ironing

The Scandinavian countries top the list when it comes to gender equality. Women in Norway, Finland and Denmark spend twice as much time doing household chores than their husbands -proof, the authors of the study say, that family-friendly policies and good child care boosts gender quality. In countries where men are the main breadwinners, women automatically do more housework.

There may be limits to the equality in housework that can be achieved under current social policy, management culture, and gender ideology constraints, the authors of the housework study admit - and conclude that in the long run, people will have to change their way of thinking.