The new structure of society is also responsible for the worsening performance of boys in school, according to Labour sociologist Norman Dennis.
He believes that earlier this century working-class boys were motivated to do their best in school because they knew their destiny was likely to be that of a husband and father who would have responsibilities as a breadwinner.
That impetus remains for girls, who know that one day they may be responsible for the upkeep of a child but, according to Dr Dennis, the current widespread attitude in society that young men can walk away from fatherhood has had many unwelcome effects on everyday life, not least on boys' academic performance.
In a new book, The Invention of Permanent Poverty, Dr Dennis, guest fellow in the department of religious studies at the University of Newcastle upon Tyne, argues that last year's Joseph Rowntree Foundation report, which blamed unemployment and poverty for rising crime figures, does not make sense.
Instead the facts show that crime levels were much lower and rose far more slowly in the 1930s, when unemployment was running three times higher than it is now. Moreover, he points out, the actual definition of poverty has changed from the most basic level of subsistence to half of average earnings.
He blames journalists, academics and other intellectuals for making respectable the changes in society which have seen the denigration of marriage and the family and rewarded single-parent families on low incomes at the expense of those headed by married couples.
This is the major change in society of the past 40 years, he says, and yet the increase in unwelcome manifestations such as crime is blamed on poverty and unemployment, which Dr Dennis says do not show the same provable rise.
Perhaps unsurprisingly, Dr Dennis's theory has proved highly controversial, particularly since it is published by the right-wing Institute of Economic Affairs (the director of its health and welfare unit happens to be a former pupil). The Rowntree Foundation has sent its information officer into the fray, and Dr Dennis himself has been accused of moralising - even though he says he "chickened out" of doing so.
As the son of a Sunderland tram driver and lifelong Labour supporter and member, he says friends and local party colleagues are surprised only that he is paid highly for producing common sense.
He is dismissive of the School Curriculum and Assessment Authority's Forum on Moral Values, which has belatedly decided that the importance of "traditional" marriage should be taught. "I don't suppose there would be anything on the curriculum other than the status quo of 1997," he said.
Dr Dennis feels strongly that working-class children and communities are the losers in all the social upheaval. Some of the disadvantages of having a lone parent can be ameliorated if that parent is in a well-paid job with lots of help: not so for children at the other end of the income scale.
When he was at elementary school in a Sunderland slum, Norman Dennis and his fellow pupils were constantly exhorted to aspire to middle-class jobs and achievements, something he believes is not considered politically correct now.
Later, when he had graduated and was living in a rough miners' hostel as a teetotal researcher, there was the same support for his ambitions. "If one of them tried to get me out drinking or poaching, the others would be absolutely furious. They'd say 'Norman is trying to make something of his life and educating himself,' and that was the attitude in my community. I think that has been undermined now."
He adds: "You can see the importance of family and strong kinship in school achievement now.
"Asian and Chinese children in working-class communities are showing a clean pair of heels to their English equivalents."
"The Invention of Permanent Poverty" by Norman Dennis is available at Pounds 11 inc pp from the IEA Health and Welfare Unit, 2 Lord North Street, London SW1P 3LB.