This is partially about attitudes, but more about time and energy. Apart from a few amazing exceptions, working-class parents don't have the same resources available as the middle class; try working 12 hours at manual labor, commuting on the bus two hours each way, and going to argue with your kids' teacher.

Consider the difference between the Hispanic-American and Asian-American communities when it comes to educational success, one slightly below average and the other considerably above. Nobody could call Hispanic-American mothers soft!

Many put this down to Confucian values, and perhaps they play a role. But it's also about the conditions under which they came into the US.

Asian-Americans have been part of the middle class in the US for two, perhaps three, generations already. Their great-great-grandparents, in some cases, might have come across as poor railway workers in California, but far more came as part of the exodus of the elite from South Korea and some Southeast Asian countries in the 1950s and 1960s. These were people who were used to being at the top of their society. Getting into the US from so far away generally meant you were, at least by local standards, already rich and connected.

In contrast, those who came from Central and South Americas were normally the poor and desperate, risking their lives in hazardous but relatively cheap border crossings for the chance of low-level jobs.

The Asian-Americans came in at the middle; the Hispanics at the bottom. Groups like the Hmong, ethnic villagers brought into the US en masse in the late 1970s by the government, are far less successful than other Asian-Americans.

So let's not pretend there's some magic secret of parenting that ensures success. As Chua's own story shows, once you dig past the hype, money, class, and power make far more difference than maternal virtue.