In “The Adventures of Huckleberry Finn,” the young protagonist gripes about his adoptive mother’s efforts to “sivilize” him — particularly at the dinner table, where he observes that each dish is cooked and served separately.

“In a barrel of odds and ends it is different;” Finn says. “Things get mixed up, and the juice kind of swaps around, and the things go better.”

I thought about that line while reading Robert Putnam’s “Our Kids,” a jarring study of the growing opportunity gap between rich and poor children. America would like to think of itself as Huck’s “barrel of odds and ends,” a kind of democratic stew. But, as Putnam shows, our society is increasingly more like his adopted mother’s meal, with each dish cooked separately and cordoned off into different compartments on the dinner plate.

“ The young and poor in America ‘are completely clueless about the kinds of skills and savvy and connections needed to get ahead.’ ” — Robert Putnam

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The upper-middle-class families Putnam profiles separate themselves into affluent suburbs, with separate public schools and social spheres from those of their poorer counterparts. As a result, the poorer children not only face greater hardships, but they also lack good models of what is possible. They are effectively cut off from opportunity.

“The most important thing about the experience of being young and poor in America is that these kids are really isolated, and really don’t have close ties with anybody,” Putnam told MarketWatch. “They are completely clueless about the kinds of skills and savvy and connections needed to get ahead.”

His analysis shows how family structure, parenting practices, schooling and health habits correlate with diminishing opportunities for poorer children.

For instance:

Children of poorer, less educated parents are far more likely to grow up in single-parent homes.

Putnam/Our Kids/S&S

Educated, wealthier parents are able to devote considerably more time to childcare.

Putnam/Our Kids/S&S

Due to lack of support networks and good models, perhaps, the highest-scoring poor children are less likely to graduate college than the lowest-scoring wealthy children.

Putnam/Our Kids/S&S

Childhood obesity has been all but eliminated among wealthier children but continues to increase in poorer families.

Putnam/Our Kids/S&S

Putnam does not fault the wealthier parents for seeking the best for their children. “Perhaps unexpectedly, this is a book without upper-class villains,” he notes.

But he makes the case that it’s not only in the moral interest of wealthier families to help improve the prospects of poorer children but also in their own economic interest. The U.S. economy would get a major boost if the opportunity gap were closed, he says. We cannot continue to live in our own bubbles, or compartments on a plate, without consequences, he suggests.

“What I hope people take away is that helping poor kids, giving them more skills and more support would economically benefit their kids,” Putnam said.

Perhaps, as Huckleberry Finn suggested at the dinner table, when we mix things up, and break down our physical and cultural class divisions, ”things go better.”

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