Teens who regularly get into fights with their parents have significantly different brain structures than their quieter peers.
Australian researchers mapped the brains of some 137 early teens and then videotaped them during "problem solving" conversations with their parents about disagreements over issues like homework, bedtimes, or Internet and cell phone use.
"What we found was there was actually a relationship between the size and the structure of the various parts of the brain and the way the kids behave in these interactions," said lead researcher Nicholas Allen of the University of Melbourne.
The parts of the brain which are involved in emotional responses were much more developed in the teens who got into fights with their parents, Allen said.
"Their emotions are developing much faster than are the parts of the brain that help them to manage those emotions," he said in a telephone interview.
"That's the kind of thing that hopefully catches up later on, but in between you've got this mismatch between the two."
The findings should offer some comfort to parents trying to understand why their once-cheerful children are suddenly transformed into sulky, over-sensitive strangers, especially since this mismatch is usually resolved by the time the brain finishes developing in the mid-20s.
"Many parents do find it a comforting thought to be told that it's not necessarily abnormal or a reflection of the child's character that they're being grumpy and surly because they are going through a biological change which is a fairly significant one," he told AFP.
"(But) there are all sorts of things that can influence grumpiness. It might be that the family has developed a poor pattern or interaction, it might be that the kid is lazy, or the kid needs to be taught more responsibility or to respect others more."
It's also possible that these biological changes are in response to the home environment, Allen said of the study published by the Proceedings of the National Academy of Sciences.
Other studies have found that extreme neglect and sexual and physical abuse can impact brain development. A stressful home environment has also been linked to the early onset of puberty in girls, he said.
"What we don't know anything about is, is there an affect about the more normal variations in the family environment on the way the brain develops," he said.
"We're not sure if the environment is affecting the biology or the biology is affecting the environment. Probably the most likely truth is they both affect each other."
Allen hopes to find some answers to these questions as his team delves deeper into a long-term study of these youth and their families.
They will be closely analyzing the family interactions to see if there is a link between parenting skills or styles and the emotional and biological development of the teens.