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We've long known the importance of giving women the chance to spend some a few weeks -- or months -- away from work and with their newborns. It turns out that giving new dads the opportunity to spend some time with their new kids is not only important for the short term but also has huge consequences for the family dynamic later on.

New research out of nnada being released Thursday shows that a small change in policy -- making it “normal” and expected  for fathers to take parental leave -- not only led men to spend more time with their new babies, but to also do more housework and pick up more child-care responsibilities down the road.

The study, authored by Ankita Patnaik, a PhD candidate in economics at Cornell University, was recently summarized in a brief called “Daddy’s Home!” written for the the Council on Contemporary Families. The study examined what happened to families when the government of Quebec in 2006 introduced a “daddy-only" quota and increased the pay in the paid parental leave policy. The share of eligible fathers taking leave at all jumped from 21.3 percent by 53 percentage points, a 250 percent increase. And the length of time fathers took off to care for infants rose from two weeks, on average, to five weeks.

[Related: Women spend 6 hours a week on housework, more than three times as much as men]

But perhaps the most surprising, and powerful finding was this: By 2010, the men in Quebec who had taken the “daddy-only” leave were spending 23 percent more time doing housework and child care than were men in other parts of Canada without the quota.

“I was struck by the magnitude of the effect that this reform had, given how small and relatively cheap the change was,” said  Patnaik. “And the persistence of the change over time was striking. If you intervene at this critical time, when parents are trying to assign household roles for the first time, you establish more gender-neutral habits. And they stick.”

Researchers have long argued that giving only mothers time off after the birth, adoption or fostering of a child reinforces the cultural belief that "mother knows best" when it comes to kids, and contributes to men spending more time at work, earning more and getting promoted more often -- and women doing the bulk of the housework and child care.

The study found that, just as fathers who had taken leave under the daddy quota were spending a half-hour a day more at home, mothers were spending a half-hour a day less at home, and had increased their time at work by nine percent. Still, Patna said, mothers reorganized their time at home, spending less time on housework and more time on child care.

[Related: Making time for kids? Study says quality trumps quantity.]

Canada gives mothers up to one year of unpaid, job-protected leave that an become paid leave through an employment insurance program; for fathers, it gives 37 weeks that can become paid leave through an employment insurance program. Under this system, fewer than 20 percent of Canadian fathers take leave. In 2006, Quebec increased the paid leave benefit from 55 percent of take-home pay to 70 percent, up to a maximum of $767 a week, and established a five-week “daddy quota.”

Although surveys show that millennial generation men, in particular, say they want to be more involved fathers than their own dads were, Patnaik said the size of the increase in those who took leave reflected more than a generational shift in fathers’ attitudes.

“I identified an immediate jump between Dec. 31, 2005, and Jan. 1, 2006,” she said. “It’s incredibly unlikely that everyone all of a sudden had egalitarian beliefs. But I do think the ‘papa quota’ made a difference. It sends the message that this is what we, as a society, think dads should be doing. This is what's normal.”

The experience of paternity leave, she said, appears to change beliefs about what dads can do around the house, and what it means to be a good dad. “Perhaps what the father quota did was facilitate those who’d always wanted to take leave, but couldn’t afford to, or worried they’d be stigmatized by their employer,” she said. “Now, we’ve given them the opportunity to do something they’d always wanted to do.”

Whether they want it or not, few fathers in the United States get paternity leave. While 58 percent of U.S. companies offer some kind of partial paid leave to mothers, only 14 percent do the same for fathers. And one in five companies don’t even offer unpaid leave to new fathers, even though federal law requires them to. The federal Family and Medical Leave Act mandates that companies with more than 50 employees give 12 weeks of unpaid medical leave to full-time workers who’ve been with the company for at least a year. The act doesn’t apply to 40 percent of the workforce.

Some 95 countries offer some form of paid parental leave to fathers, Patnaik said. And those with some of the highest rates of fathers taking parental leave have the “daddy-only” quota that Quebec instituted or other policies aimed at men. The United Kingdom is instituting a new policy this month to promote more shared leave between mothers and fathers. In Sweden, where 45 percent of fathers took paid parental leave in 2013, parents receive a financial bonus if they not only share the leave but also share the time equally.

In Iceland, mothers used to have long maternity leaves, and three years later, were still responsible for doing most of the child care. When the country adopted a “daddy days” quota, giving mothers and fathers three months of paid leave each, and three months for the family to share – nine months total – Iceland mandated that if fathers didn’t use their three months, the family would lose the time.

Now, 90 percent of fathers take paid leave in Iceland. And three years after the birth of a child, 70 percent of the parents who lived together equally shared child care.

This article has been updated to clarify that both men and women are eligible for paid leave when they have a child.

Read more:

Couples who share housework have the most sex and best sex lives

I’m a dad. So why do people call me ‘Mrs.’?

More than a paycheck: New dads want paid leave to be caregivers