Married couples are most likely to be happy with their relationships compared with other couples, while marriage breakdown does more damage to children than living in poverty, according to a new study published yesterday.

The study, which is tracking members of 40,000 households across Britain, found that children who grow up in a traditional two-parent family and regularly eat an evening meal with their parents are more likely to be happy with their lives than their peers.

The study reinforced the central importance of the traditional family unit to children’s development.

“Not living with both natural parents has a greater negative impact on a young person’s life satisfaction than their material situation,” it said.

“Parents’ relationships between each other and with their children are important for children’s cognitive and emotional development and the stability of families.

“Children are happier with their family situation if their parents are happier with their relationship with each other.”

The findings are among the first results to emerge from Understanding Society, a £50 million, government-funded study following the lives of 100,000 people in 40,000 households across the country.

Conducted by academics from the universities of Essex, Oxford, Warwick and Surrey, the research details attitudes towards politics, climate change, family relationships, work, health and education. The first wave of findings, released today, comes ahead of the government’s own separate initiative to measure national well-being, which will be launched in April.

However, bullying between siblings is widespread, and can have a severe impact on children’s behaviour and performance at school, and their mental health, the study said. Children from step families are more likely than others to be bullied.

The researchers stressed that it is crucial for children’s well-being that they are able to discuss important issues with at least one of their parents and not to quarrel too often.

The report continued: “Eating an evening meal together as a family is important. Children who eat an evening meal with their family at least three times a week are substantially more likely to report being completely happy with their family situation than children who never eat with their family, or who eat together less than three times a week.”

David Cameron has promised to recognise the importance of stable relationships with tax breaks for married couples and those in civil partnerships. Under government plans, all couples seeking a divorce will be required to consider relationship mediation sessions before going to court.

Findings from the Understanding Society project, based on an initial survey of 35,000 people in 14,000 households, showed that happiness declines with the length of a relationship, with women’s satisfaction levels falling more sharply than men’s.