... As this year’s summer vacation begins, many parents contemplate how to rein in their kids. But there was a time when Americans pushed in the opposite direction, preserved in Mark Twain’s cat-swinging scamps. Parents back then encouraged kids to get some wildness out of their system, to express the republic’s revolutionary values.

American children of the 19th century had a reputation. Returning British visitors reported on American kids who showed no respect, who swore and fought, who appeared — at age 10 — “calling for liquor at the bar, or puffing a cigar in the streets,” as one wrote. There were really no children in 19th-century America, travelers often claimed, only “small stuck-up caricatures of men and women.”

This was not a “carefree” nation, too rough-hewed to teach proper manners; adults deliberately chose to express new values by raising “go-ahead” boys and girls. The result mixed democracy and mob rule, assertiveness and cruelty, sudden freedom and strict boundaries.

Visitors noted how American fathers would brag that their disobedient children were actually “young republicans,” liberated from old hierarchies. Children were still expected to be deferential to elders, but many were trained to embody their nation’s revolutionary virtues. “The theory of the equality” was present at the ballot box, according to one sympathetic Englishman, but “rampant in the nursery.” ...