A mother's level of contentment has a far greater impact than the father's on the happiness of the whole family, a new study has found.
Research by the Marriage Foundation revealed that the mother's happiness is also far more important when it comes to the mental health of the children and her closeness to them in their teenage years.
The study was carried out by Marriage Foundation research director Harry Benson and the University of Lincoln's Professor Steve McKay, and analysed the data of 13,000 UK families from the Millennium Cohort Study.
The findings suggest an especially strong link between the mother's happiness during the first year of her child's life and her levels of happiness later on in life.
The researchers found that mums who reported a high level of happiness when their child was nine months old were far more likely to have a good level of happiness when their child was a teenager.
There was also evidence that happy mothers were more likely to have a stable relationship with their children's father, while their children were less likely to have mental health problems.
The parents taking part in the study included both cohabiting and married couples who had a child born in 2000 or 2001.
They were questioned six times from the time their children were nine months old up until they reached the age of 14.
Questions examined how happy the parents were with their relationship when their child was nine months old and again 14 years later, as well as whether they had stayed together during this period and whether their teenage children were showing signs of mental health problems.
Parents were also asked about how close their relationship was with their teenage children.
Overall, the researchers said that the mother's happiness was twice as important as the dad's when it came to the family's wellbeing and was more significant than whether the parents were married or not.
Mr Benson said it was evidence that the popular slogan 'happy wife, happy life' had some truth to it.
"I've always argued that the key to happy family life is for dad to love mum and she will love him right back, in that order. Previous research has supported this idea but it's been bitty," he said.
"We think this is the first serious attempt to test the truth of the saying 'happy wife, happy life' across four different family outcomes.
"Equality has been excellent for encouraging women into work and men into childcare. But many men now struggle to find a unique role for themselves in family life.
"This research suggests a compelling solution. Men, the best thing you can do for your family is to love the mother of your children. Happy wife, happy life."
Sir Paul Coleridge, former high court judge and chairman of the Marriage Foundation added: "As with so many traditional family myths, there is more than a grain of truth in this one as the evidence demonstrates.
"In all the contemporary discussion about the appropriate roles for mums and dads in today's well-adjusted family, it is still crucial not to forget the vital role of wife/mother as the lynch pin.
"Dads would do themselves and their children a favour if they bore in mind that being supportive and kind to the mother of their children is not a sign of weakness but strength and self-confidence."