Lowell, Massachusetts, a former mill town of the red-brick-and-waterfall variety 25 miles north of Boston, has proportionally more Cambodians and Cambodian-Americans than nearly any other city in the country: as many as 30,000, out of a population of slightly more than 100,000. These are largely refugees and the families of refugees from the Khmer Rouge, the Maoist extremists who, from 1975 to 1979, destroyed Cambodia’s economy; shot, tortured, or starved to death nearly two million of its people; and forced millions more into a slave network of unimaginably harsh labor camps. Lowell’s Cambodian neighborhood is lined with dilapidated rowhouses and stores that sell liquor behind bullet-proof glass, although the town’s leaders are trying to rebrand it as a tourist destination: “Little Cambodia.”

At Arbour Counseling Services, a clinic on a run-down corner of central Lowell, 95 percent of the Cambodians who come in for help are diagnosed with Post Traumatic Stress Disorder, or PTSD. (In Cambodia itself, an estimated 14.2 percent of people who were at least three years old during the Pol Pot period have the disorder.) Their suffering is palpable. When I visited Arbour, I met a distraught woman in her forties whom I’ll call Sandy. She was seven when she was forced into the jungle and 14 when she came to the United States, during which time she lived in a children’s camp, nearly starved to death, watched as her father was executed, and was struck in the ear by a soldier’s gun. She interspersed her high-pitched, almost rehearsed-sounding recitation of horrors past with complaints about the present. She couldn’t concentrate, sleep at night, or stop ruminating on the past. She “thinks too much,” a phrase that is common when Cambodians talk about PTSD. After she tried to kill herself while pregnant, her mother took Sandy’s two daughters and raised them herself. But they have not turned out well, in Sandy’s opinion. They are hostile and difficult, she says. They fight their grandmother and each other, so bitterly that the police have been called. They both finished college and one is a pharmacist and the other a clerk in an electronics store. But, she says, they speak to her only to curse her. (The daughters declined to talk to me.)

On the whole, the children of Cambodian survivors have not enjoyed the upward mobility of children of immigrants from other Asian countries. More than 40 percent of all Cambodian-Americans lack a high school diploma. Only slightly more than 10 percent have a bachelor’s degree. The story of Tom Sun, a soft-spoken, pop-star-dapper thirtysomething (he doesn’t know his exact age) is emblematic, except, perhaps, in how well he’s doing now. His mother was pregnant with him during the Khmer Rouge years. His father died before the Vietnamese invaded Cambodia and drove the Khmer Rouge back into the jungle. When he was very young, he, his mother, and a little brother made their way from a Thai refugee camp to the United States and eventually settled in Lowell. The two boys and two other brothers, born after they arrived in the United States, were left to raise themselves. Illiterate and shattered, their mother gambled, cried, and yelled at her sons. “My mother, she’s loud,” Sun told me. “She’s got a very mean tone. I still hear it in my head.” His stepfather, a mechanic, also a survivor and also illiterate, beat them until welts striped their bodies. By the time Sun should have entered seventh grade, he had joined the Tiny Rascals, perhaps the largest Asian American street gang in the United States. “It was comforting,” he says. “We weren’t into drugs or alcohol.” They were into being a substitute family. They were also into guns. Sun was involved in a shooting that led to a stint in prison, which led to a GED, some college credits, and some serious reflection on his future. He left the gang in his mid-twenties. His brothers were not so lucky. Two of them are serving life sentences for murder.

The children of the traumatized have always carried their parents’ suffering under their skin. “For years it lay in an iron box buried so deep inside me that I was never sure just what it was,” is how Helen Epstein, the American daughter of survivors of Auschwitz and Theresienstadt, began her book Children of the Holocaust, which launched something of a children-of-survivors movement when it came out in 1979. “I knew I carried slippery, combustible things more secret than sex and more dangerous than any shadow or ghost.” But how did she come by these things? By what means do the experiences of one generation insinuate themselves into the next?

Traditionally, psychiatrists have cited family dynamics to explain the vicarious traumatization of the second generation. Children may absorb parents’ psychic burdens as much by osmosis as from stories. They infer unspeakable abuse and losses from parental anxiety or harshness of tone or clinginess—parents whose own families have been destroyed may be unwilling to let their children grow up and leave them. Parents may tell children that their problems amount to nothing compared with what they went through, which has a certain truth to it, but is crushing nonetheless. “Transgenerational transmission is when an older person unconsciously externalizes his traumatized self onto a developing child’s personality,” in the words of psychiatrist and psychohistorian Vamik Volkan. “A child then becomes a reservoir for the unwanted, troublesome parts of an older generation.” This, for decades, was the classic psychoanalytic formulation of the child-of-survivors syndrome.