London - Divorce could be in the genes, with children of separated parents "programmed" to split up as well, according to a study.
It has been thought that children of divorce are twice as likely to get divorced themselves because they do not have happily married parents as role models.
But though this may have an influence, a study has found there are strong biological reasons too.
While there is no "divorce gene", the personality traits that often cause marriages to break up – such as extreme negativity or lack of self-restraint – may be written in our DNA and passed on from parents to their children.
Researchers at Virginia State University in the US and Sweden’s Lund University tested the genetic theory by looking at the marital histories of more than 20 000 adopted children.
They found that these children were more likely to resemble their biological parents and siblings than their adoptive families when it came to whether they ended up being divorced – suggesting nature is more important than nurture.
Co-author Dr Kenneth Kendler, of Virginia State University, said: "I see this as a quite significant finding.
"Nearly all the prior literature emphasised that divorce was transmitted across generations psychologically.
"Our results contradict that, suggesting that genetic factors are more important." To further test their genetic hypothesis, the researchers looked at 82 698 people who grew up with their biological mother but had an absent father.
They found that such children were still influenced by their father’s divorce history.
However their own divorce history was more similar to their mother’s, suggesting the person they grew up with still mattered to a degree above their genetic inheritance.
The researchers said that divorce is linked to those who experience rollercoaster emotions, with high levels of negativity and positivity, and low levels of self-restraint. These personality traits can lead to marital problems and instability and could be passed on to children through their parents’ genes, they wrote in the journal Psychological Science.
More than 101 000 marriages end each year in England and Wales, although the divorce rate has plunged to its lowest level in modern times as rising numbers of couples choose to live together instead of walking down the aisle.
Researchers have repeatedly found that children of divorce are more likely to end their marriages, but debate rages over whether this is learned from parents or inherited from their genes. Study lead author Dr Jessica Salvatore said: "At present, the bulk of evidence on why divorce runs in families points to the idea that growing up with divorced parents weakens your commitment to and the interpersonal skills needed for marriage.
"These previous studies haven’t adequately controlled for or examined something else in addition to the environment that divorcing parents transmit to their children – genes.
"Our study is, at present, the largest to do this.
"And what we find is strong, consistent evidence that genetic factors account for the intergenerational transmission of divorce."