A bad classmates can hurt you.

Joanne Jacobs reports.

Disruptive kids lower classmates’ future earnings

Exposure to a disruptive classmate in elementary school reduces earnings at age 26 by 3 to 4 percent, according to a working paper, The Long-Run Effects of Disruptive Peers.

One disruptive student in a class of 25 also lowers high school test scores, college attendance and degree attainment, researchers concluded.

Coming from a violent family was used as a proxy for disruptive behavior, because research shows “children exposed to domestic violence are associated with a number of emotional and behavioral problems including aggressive behavior, bullying, depression, animal cruelty, diminished academic performance, and violence in adulthood,” researchers wrote.