Marriage itself does little to promote the development of children, a think tank has suggested.
According to a new study from the Institute for Fiscal Studies, while youngsters brought up by parents in wedlock do tend to progress faster, this is because of other factors.
For example, couples who tie the knot tend to be better educated, earn more and have more stable relationships than those who do not, it claimed.
The organisation - which has been in operation for 40 years and is an independent microeconomic research institute - based the findings of its Cohabitation, Marriage and Child Outcomes report on the Millennium Cohort Study.
It discovered that married mothers and fathers were twice as likely to have gone to university as cohabiting pairs and were also more likely to own their own home.
The study's authors said: "We have ... shown that parents who are married differ from those who are cohabiting in very substantial ways, particularly relating to their ethnicity, education and socio-economic status and their history of relationship stability."