Developmental disord. Dyslexia is a disorder of symbol identification. Children are born with this disorder. There are a number of specialized reading programs available to help overcome dyslexia. It is possible to develop dyslexia as a result of a brain injury as well.
90% of the time. Dyslexia is a language-based reading disorder, from dysfunction in the part of the brain that processes phonemes, the smallest units of sound in a language, in a child with an average or above-average IQ. 10% of cases are from visual-perceptual problems. The "set-up" is either genetic or epigenetic, exposure to agents that alter function, but not structure or sequence of fetal genes.
Born With. The likelihood of having dyslexia is something that is internal or within the individual. However, the severity or expression of dyslexia is definitely made worse by experiences and circumstances in the environment.
Some inherited. Dyslexia broadly divides into two groups. One is acquired: eg, after a stroke or other insult to the left temporal lobe of the brain. The other is an inherited neurological problem that prevents proper decoding of letters or words into ideas. Some conditions can mimic dyslexia, such as ad/hd or specific learning disabilities. Many dyslexics have family members with it too.