In the 1990s, Vincent Felitti and Robert Anda conducted a study on adverse childhood experiences. They asked 17,000 mostly white, mostly upscale patients enrolled in a Kaiser H.M.O. to describe whether they had experienced any of 10 categories of childhood trauma. They asked them if they had been abused, if their parents had divorced, if family members had been incarcerated or declared mentally ill. Then they gave them what came to be known as ACE scores, depending on how many of the 10 experiences they had endured.

The link between childhood trauma and adult outcomes was striking. People with an ACE score of 4 were seven times more likely to be alcoholics as adults than people with an ACE score of 0. They were six times more likely to have had sex before age 15, twice as likely to be diagnosed with cancer, four times as likely to suffer emphysema. People with an ACE score above 6 were 30 times more likely to have attempted suicide.

Later research suggested that only 3 percent of students with an ACE score of 0 had learning or behavioral problems in school. Among students with an ACE score of 4 or higher, 51 percent had those problems.

In Paul Tough’s essential book, “How Children Succeed,” he describes what’s going on. Childhood stress can have long lasting neural effects, making it harder to exercise self-control, focus attention, delay gratification and do many of the other things that contribute to a happy life.