Children follow their mother's example when it comes to the number of romantic relationships they have, researchers have found.
A new study, the largest ever of its kind, found children of women who change partners regularly are likely to follow suit, while those who favour long-term relationships tend to have mothers who behaved similarly.
However, scientists are at a loss to explain why.
While it is already known that children of parents who divorce are more likely to divorce themselves compared to those whose mother and father stay married, this is the first study to show how closely the number of relationships a person has correlates across the generations.
Previous research has also suggested that economics explains the link, the idea being that the financial insecurity that often comes with a mother who frequently changes partners damages the child emotionally, making it harder for him or her to settle down themselves.
However, the new study, published in the journal PLOS One, adjusted for this, indicating there is a more fundamental reason why children follow their mothers' example, the Daily Telegraph reports.
The findings by the University of Ohio come from analysis of more than 7,000 people over 24 years.
"It's not just divorce now - many children are seeing their parents divorce, start new cohabiting relationships, and having those end as well," said Professor Claire Kamp Dush, who led the research.
"All of these relationships can influence children's outcomes, as we see in this study."
Both the number of marriages and the number of cohabiting partners by mothers had similar effects on how many partners their children had, the study found.
However, results showed that siblings exposed to their mothers' cohabitation for longer periods had more partners than their siblings exposed to less cohabitation.
"You may see cohabitation as an attractive, lower-commitment type of relationship if you've seen your mother in such a relationship for a longer time," Kamp Dush said.
"That may lead to more partners since cohabiting relationships are more likely to break-up."