Want to make your parents happy? Move out.

New research suggests people with kids are happier in their later life than people without children, but only if their children have left the nest.

Scientists at Heidelberg University in Germany used data on 55,000 people ages 50 and older in 16 European countries. The information came from the Survey of Health, Ageing and Retirement in Europe database.

The results, published in journal PLOS One, suggest that parenthood makes people happier as they age. One reason could be that parents see their grown children as a form of social support that "may become important in the later states of a person's life."

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Past surveys have focused on parents whose kids still live at home. These often show that people with kids aren't as happy as their childless peers because they have less free time, sleep and money.

But Christoph Becker and his team found that "when children grow up and move out, they provide social enrichment to their parents minus the day-to-day stress of looking after them." Grown children may also give something back by providing care and financial support to their parents, he said. "Hence, children's role as caregivers, financial support or simply as social contact might outweigh negative aspects of parenthood."

Becker told CNN that "having a social network corresponds to greater life satisfaction, but that doesn't have to come from children."

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People without children can get enough social satisfaction from close relationships with friends or family members.

CNN wrote that Becker plans to track happiness for the same people over many years to study how well-being changes as people age.

"Literature has suggested that there might be U-shaped connection between age and happiness: people become less happy in middle age, but more happy in older age," Becker told CNN. "We want to test if we find a similar relationship in our data, depending again on parenthood and social networks."

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