Fathers who have daughters will shift their political views left while those who have sons will become more right-wing, a British study has found.
Researchers from the Warwick and York Universities found that the more daughters there were in a household, the more likely their father was to vote Labour or the centre-left Liberal Democrat.
In an unpublished paper that has been submitted to an economics journal, Professor Andrew Oswald and Dr Nattavudh Powdthavee said: "This paper provides evidence that daughters make people more left-wing, while having sons, by contrast, makes them more right-wing."
The academics go on to speculate that left-wing families become so through a predominance of females down successive generations.
The study showed that in Britain, compared with males, females tended to be more in favour of higher taxes to fund provisions such as the country's health service.
Higher taxation also affects them less since they tend to be in a lower income bracket.
"As men acquire female children," said Professor Oswald, "those men gradually shift their political stance and become more sympathetic to the 'female' desire for a ... larger amount for the public good. They become more leftwing. Similarly, a mother with sons becomes sympathetic to the 'male' case for lower taxes and a smaller supply of public goods. Political feelings are much less independently chosen than people realise," he added.
"Children mould their parents. It's so scientifically attractive because it's out of the parents' control - whether they have a boy or a girl."
The study was based on data from the British Household Panel Survey.
Their work mirrors recent findings by American researchers, who looked at the voting records of US congressmen before and after having children. In a joint paper, sociologist Rebecca Warner from Oregon State University and the economist Ebonya Washington from Yale University found that support for policies designed to address gender equity is greater among parents with daughters. The result, they say, is particularly strong for fathers.
Because parents invest a significant amount of themselves in their children, the authors argue, the anticipated and actual struggles that offspring face, and the public policies that tackle those, begin to matter more to those parents.
They add that people who parent only daughters are more likely to hold feminist views, with congressmen who have female children tending to vote liberally on issues from reproductive rights and teenage access to contraceptives to flexibility for working families and education.
Professor Oswald said: "I argue that these results generalise to voting for entire political parties. We document evidence that having daughters leads people to be more sympathetic to left-wing parties. Giving birth to sons, by contrast, seems to make people more likely to vote for a right-wing party."
There are those who dispute the interpretation of the findings, but evidence nonetheless abounds of daughters who have tamed the most manly of men. When rapper Sean (P Diddy) Combs and his girlfriend Kim Porter had identical twin daughters two years ago, the New York musician admitted that "having girls changes you for the better".