I'm studying psychology, and we have recently been dicussing childhood development, reading and language.
According to most recent evidence, dyslexia is no different to people with poor reading skills, regardless of their IQ. Apparently if babies are not talked to often, particularly with 'baby talk' then they do not learn the phonetic alphabet, and can never really understand them properly after vital stages. Thought I'd just throw that in there ;)
Is your family bi-lingual? This can often slow development of language quite a lot. However when they do begin talking, they develop a lot quicker than their none bi-lingual peers.