Adjusting to a new country often more difficult for teens _ a factor in the Boston bombings?

In this image provided by Anna Tabakh, she and her older brother, Ilya, stand with their family after arriving at the Kansas City, Mo. airport in December 1990, a year before the collapse of the Soviet Union. At age 5, Anna didn't know a word of English, en route with her parents from the Soviet Union to a new home in Kansas City, Mo. The beginning was traumatic, she says, now 27, but the transition to American life was relatively smooth - a result that some social scientists would say was partly due to her age. (AP Photo/Anna Tabakh) (The Associated Press)

In this image provided by Anna Tabakh, she, foreground left, and her older brother Ilya, foreground right, stand with their family after arriving at the Kansas City airport in December 1990, a year before the collapse of the Soviet Union. At age 5, Anna didn't know a word of English, en route with her parents from the Soviet Union to a new home in Kansas City, Mo. The beginning was traumatic, she says, now 27, but the transition to American life was relatively smooth - a result that some social scientists would say was partly due to her age. Back row from left are her mother, Diana Tabakh; her aunt, Mila Portman; cousin, Boris Portman; and her father's cousin, George Portman; and her father, Eugene Tabakh. (AP Photo/Anna Tabakh) (The Associated Press)

FILE - In this undated photo provided by Robin Young, Dzhokhar A. Tsarnaev, left, and Here & Now host Robin Young's nephew, right, pose for a photo after graduating from Cambridge Rindge and Latin High School. Tsarnaev was about 9 when he came to the United States from the Russian Caucasus region. He was more integrated in daily American life than his older brother, according to accounts from friends and relatives. (AP Photo/Robin Young) (The Associated Press)