Google the question “Are more boys than girls dyslexic” and you’ll get urban myth laced with moralizing—not science or good psychology. To say that boy brains and girl brains of dyslexics work the same way in roughly the same proportion is as credible as reports of giant alligators swishing through New York City’s sewer system. This update is intended to help parents, psychologists, and educators move toward diagnosing and treating developmental dyslexia with a clearer understanding of what we know today.
More Boys Are Dyslexic
“Yes!” More boys are dyslexic. And it may make a difference for both diagnosis and treatment as well as for research.
We need to end the urban myth. The question, regarding whether more boys than girls are dyslexic has been answered. The problem is that when you Google “Are More Boys than Girls Dyslexic?” the first sites that likely come up give an incorrect answer:
The venerated Public Broadcasting Service site PBS Parents  is wrong. Here’s what you get:
"It was once thought that dyslexia is more common in boys than in girls, but recent research has shown that this is not the case. (Gentry aside: Is a 1990 study recent research?) An equal number of girls and boys are dyslexic. (Gentry aside: Not so! Reading impairment is more common in males than in females.) It is thought that boys are more likely to act out as a result of having a reading difficulty and are therefore more likely to be identified early. Girls, on the other hand, are more likely to try to "hide" their difficulty, becoming quiet and reserved." 
A University of Michigan “Dyslexia Help” web site is unwavering:
"Although it used to be thought that more boys experienced dyslexia than girls, current research has indicated that dyslexia occurs in approximately equal proportions. One possible explanation of this myth is that boys may be more likely to act out when experiencing difficulty, while girls may try to hide their trouble. Therefore, more boys would be recognized and diagnosed with dyslexia, falsely inflating the statistics." 
Wrong, wrong, wrong. Sites like these perpetuate the myth!
How Did We Get this All Wrong?
An influential 1990 study by Shaywitz and others in the Journal of the American Medical Association  posited that dyslexia only seemed to be far more common in boys due to school identification procedures. Dr. Sally Shaywitz continued to advance the referral bias notion purporting that there was no significant difference in the prevalence of reading disability in boys and girls in her widely touted book Overcoming Dyslexia (2003) . She received a great deal of media attention including features in Time and Newsweek magazines along with morning talk shows on major USA networks.
The Science is Not Muddled! Dyslexia is 2 to 3 Times More Prevalent in Males
But in 2004 there was a little touted reverse in the science. In a less known but highly respected study in 2004 Ritter and his colleagues found that dyslexia was two to three times more prevalent in males than females . Of equal significance is the finding that school identification of dyslexia is extremely poor. In their 2013 study, Quinn and others report the following:
"Perhaps the most surprising and potentially troubling result from the study (Quinn et al., 2013) was how few students who met research-based criteria for reading impairment were identified as learning disabled by their schools. Fewer than 20% of students we identified as meeting an operational definition of reading impairment were also identified as learning disabled by their schools." 
Today most educators and many psychologists remain uninformed.
Are Female and Male Dyslexic Brains the Same?
They are not according to Dr. Guinevere Eden, Professor of Pediatrics at Georgetown University Medical Center and Director of the Center for the Study of Learning who is doing fascinating brain imaging anatomical studies to find the answers.  She points to profound differences in the brain structure of males and females: Brains of female dyslexics differ from female non-dyslexics in ways that do not reflect the differences observed in males with and without dyslexia. Perhaps we should get Dr. Eden and others on the morning talk shows.
The bottom line is that sex matters—even when it comes to dyslexia!
 Shaywitz, S. E., Shaywitz, B., Fletcher, J., & Escobar, M. D. (1990). Prevalence of reading disability in boys and girls. Journal of the American Medical Association, 264, 998–1002.
 Shaywitz, S. E., (2003). Overcoming Dyslexia: A New and Complete Science-Based Program for reading Problems at Any Level. New York: Knopf.
 Rutter, M., Caspi, A., Fergusson, D.M., Horwood, L.J., Goodman, R., Maughan, B., et al. (2004). Gender differences in reading difficulties: Findings from four epidemiology studies. Journal of the American Medi0063al Association, 291, 2007-2012.
 Quinn, J., & Wagner, R. (2013). Gender differences in reading impairment and in the identification of Impaired Readers: Results from a large-scale Study of at-risk readers. Journal of Learning Disabilities, XX(X) 1–13. DOI: 10.1177/0022219413508323 journaloflearningdisabilities.sagepub.com
 Evans T. M., Flowers D. L., Napoliello E. M., & Eden G. F. (2013). Sex-specific gray matter volume differences in females with developmental dyslexia. Bain Struct Funct. 2013 Apr 27. [Epub ahead of print] PMID: 23625146
Dr. J. Richard Gentry is the author of Raising Confident Readers, How to Teach Your Child to Read and Write–From Baby to Age 7. Follow him on Facebook, Twitter, and LinkedIn and find out more information about his work on his website.