Now, the first study of its kind has found that most are psychologically healthy, though they're at "slightly increased risk" for behavioral problems such as attention deficit hyperactivity disorder or oppositional defiant disorder.

NPR: Adopted Teens Face Higher Risk for ADHD

Another effect: behavioral abnormalities such as attention-deficit disorder.

CNN: THE GREAT DIOXIN SCARE

"You've got all these young kids running around with this diagnosis, yet many of them have never, ever had a manic episode, which is the hallmark of bipolar disorder, " said Carroll, now the scientific director of the Pacific Behavioral Research Foundation.

CNN: Are we over-diagnosing mental illness?