Genetic differences in the brain make learning to read a struggle for children with dyslexia. Luckily, most of our brain development occurs after we're born, when we interact with our environment. This means that the right teaching techniques can actually re-train the brain, especially when they happen early.
May, T.S. (2006). Dissecting Dyslexia. BrainWork, the Neuroscience Newsletter from the Dana Foundation.