Answer to Question 1
A recent study of 4,000 Australian twins has provided evidence that strongly supports the view that genetic factors contribute to ADHD. The concordance rate for MZ twins was 80 percent; whereas the rate for DZ was 40 percent. These concordance rates are close to what one would expect for a purely genetic disorder. Genetic factors explain 90 percent of the variance of ADHD symptoms. At this point, however, a specific gene (or genes) responsible has not been isolated.
Answer to Question 2
Few children or adolescents identify themselves as having an emotional or behavioral problem. Instead, some adult, often a parent or teacher, decides that the child has a problem. Sometimes, a child is unable to recognize or admit to his or her difficulties. Other times, however, the problem is as much the adult's as the child's. For example, a stressed parent may have trouble coping with normal misbehavior. This can make it challenging to figure out where the problem lies.
Experimental Evidence for Infrared Radiation
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Genetic and environmental interactions in ototoxic deafness