Patricia Cohen has a great NY Times article on the resurgence of cultural explanations for generational poverty. Conservatives (as Cohen states) never abandoned the obvious connection between culture and poverty,
But in the overwhelmingly liberal ranks of academic sociology and anthropology the word "culture" became a live grenade, and the idea that attitudes and behavior patterns kept people poor was shunned.
Most interesting is not the sudden liberal awakening to culture as a factor in economic success, nor the pathological ideology which kept liberals blind to this common-sense explanation for decades, but rather the oppressive censorship and dogmatic ideological rigidity present in academics and among the left.
Of course, the left is only taking baby steps toward sensibility and reality. While acknowledging the relevance of culture, "they attribute destructive [cultural] attitudes and behavior not to inherent moral character but to sustained racism and isolation." One couldn't expect it would be long before racism was called upon to explain everything. Baby steps.
UPDATE: For an even more cynical perspective on the supposed reformation of liberal thought on poverty, see the Heritage Foundation's Robert Rector on NRO. Spoiler: liberals still think poverty is the reason for poverty - and the solution is thus to simply throw around more (of other people's) money. Rector identifies the most obvious culprit leading to poverty as "the collapse of marriage."
In low-income communities, the overwhelming majority of children are born outside marriage and raised by single mothers on welfare. If these single mothers were married to the actual fathers of their children, two-thirds would immediately be lifted out of poverty. But, despite these obvious facts, the Left is reluctant even to mention the connection between marital collapse and poverty.
The main problem for liberals in talking about the "culture of poverty" is that any honest examination of behavioral roots of poverty will, almost certainly, diminish public support for the welfare state. Thus, any clear discussion of the links between poverty and behavior is to be scrupulously avoided.