In 1965 a report from within the US government noted that the number of children born outside marriage, and the number of divorces, in the parts of the American population were rising rapidly. It argued that having many households run by a single woman risked holding back the progress of the next generation. At the time it was very controversial, rejected by mainstream academia and described as victim blaming. More than fifty years on, from the 'Moynihan' report we look at what modern research tells us about how children develop with married, cohabiting and single parents. Is there really a marked difference in their behaviour, cognition or emotional development?