A learning disability is a disorder that inhibits or interferes with the skills of learning, including speaking, listening, reading, writing, or mathematical ability. Legally, a learning-disabled child is one whose level of academic achievement is two or more years below the standard for his age and IQ level. It is estimated that anywhere from five to 20% of school-age children in the United States, mostly boys, suffer from learning disabilities (currently, most sources place this figure at 20%). Often, learning disabilities appear together with other disorders, such as attention deficit/hyperactivity disorder (ADHD). They are thought to be caused by irregularities in the functioning of certain parts of the brain. Evidence suggests that these irregularities are often inherited (a child is more likely to develop a learning disability if other family members have them). However, learning disabilities are also associated with certain conditions occurring during fetal development or...