posted on Mar, 15 2005 @ 10:00 PM
Dyslexia is not associated with any tendency towards higher or lower intelligence.
Depending on the IQ test (there are several, some much better than others), the verbal portion may have a greater weight on the global IQ score of the
test. If this was the case, some dyslexics may end up getting IQ scores that are not the best reflections of their underlying intelligence. However,
that is only a concern if a significant part of the total weight of the IQ was determined by a section containing reading. In these cases, dyslexics
may end up with an underestimated IQ score.
Nonverbal tests are often better proxies of intelligence than verbal tests (which are still good).
I'm not sure where you got the figure about a higher incidence of dyslexia in twins. I honestly don't know about that relationship. However, I have
a feeling that what you read was that the incidence of dyslexia is higher in one identical twin if the other identical twin has been diagnosed with
dyslexia. If identical twins tend to have dyselxia together more often that fraternal twins have dyslexia together, this trend suggests that there are
genetic factors contributing to dyslexia.
It is very likely that dyslexia is rooted (mostly) in genes. Many aspects of reading ability are controlled by genes, and environment doesn't seem to
have any great effect on them.
If you have any questions of doubts, PM me, and I can send you references. This thread is interested to me, as I work on a behavior genetics project
focusing on verbal, quantitative, and general mental ability.
[edit on 15-3-2005 by phaedrusxxx]