If your husband won't do the washing up, blame your sister-in-law. Or her parents.
Men who have sisters are less likely to perform housework and more likely to fulfil traditional gender roles, researchers claim.
Not only are they less likely to get out the ironing board, they are more likely to hold right-wing views, according to the American study.
The research, published by academics at Stanford Business School and Loyola Marymount University, is part of a new wave of evidence that women have a profound influence on men's outlook.
Sisters, daughters and wives all have a distinct impact on the way men behave at work and in the home, sociologists think.
The study found men who only had sisters were 6.6 per cent less likely to do the dishes at home.
The researchers think that difference goes back to childhood.
Young daughters are more likely to be asked to help in the house, they say, and the habit of watching their sisters work prevails for boys into adulthood.
Women's political views and willingness to do housework, on the other hand, is unaffected by their sisters.
The paper, published in the Journal of Politics, used data from a large study which tracked the views and habits of thousands of American families over three decades from 1965 until 1997.
The authors wrote: "Younger sisters have been found to make male siblings less likely to be assigned to female-stereotyped tasks. This effect emerged in a striking way for boys.
"In summary, we find that having sisters makes males more politically conservative in terms of gender role attitudes and partisanship.
"Particularly for gender role attitudes, we find that these effects persist into adulthood."
Other recent studies have found that having a son or a daughter can change the behaviour and attitude of a new father.
Research by scientists at the University of Maryland has found that male bosses pay themselves more and their employees less after having a new son, a natural inclination of a new father providing for their family.
But if a CEO's first child is a daughter the trend does not apply - he will actually pay his staff more, giving women the biggest pay rise.
A third study found that daughters are not only likely to make a father more generous, they also make him less attached to gender stereotypes.
Other research suggests that men with stay-at-home wives tend to disapprove of women in the workplace and are more likely to overlook qualified women for promotion.
But conversely, women in the workplace can have an impact on the way men behave at home.
A paper presented by the American Sociological Association last summer found that men take on more housework after switching from a male-dominated occupation - such as construction or engineering - to one dominated by women, such as nursing or teaching
- DAILY MAIL