What Causes Dyslexia? 4 Simple Explanations:

22 February, 2016 MARIANNE MULLALLY – What Causes Dyslexia?

Figuring out What Causes Dyslexia may feel like a complex and overwhelming task. This simple explanation might put it into perspective.

Having worked with dyslexics for over ten years and being the parent of a dyslexic, it’s one of the questions that frequently comes up in conversation, what causes dyslexia?

So What Causes Dyslexia?

No. 1 – Genetics

Like many character traits, dyslexia is genetic – meaning that it runs in families.  Even though I or my husband don’t suffer from dyslexia, I was unaware that my brother-in-law, uncles-in-law and many cousins-in-law all have dyslexia.  In fact, out of a generation of 11 children from 3 siblings, four are dyslexic.  Then from the next generation down of which there are 15 children, 5 are dyslexic.

There doesn’t seem to be any pattern to what caused the dyslexia, but certainly the genetic link is there, so we have to look further as to what else was going on to cause dyslexia.

When I consider my three children only one, the eldest, developed a ‘learning difficulty’ we later found out as dyslexia.  That’s another tricky thing.  When he was younger and struggling with his reading, the school counsellor and two psychologists diagnosed him as having a ‘Specific Learning Disability’, but specifically, they couldn’t tell me what it specifically was or how we could help him.  So dyslexia as a diagnosis is really hard to come by and unless a condition has a name, how can we start to deal with it?

Back to my three children and why one was dyslexic.  Well, the dyslexic is a “he” whereas my other children are “she’s”.  Could that be the cause of dyslexia, the fact that males have it, not females?  Well, statistically according to 2004 research by Rutter[1], dyslexia was two to three times more prevalent in males than females.  So that could certainly be a factor, but is it a cause?

So my beautiful little boy, merely by the fact that he has an X and a Y chromosome is destined never to read?  That didn’t make sense to me, especially since out of his generation of 15, 8 are boys, but only 3 are dyslexic.  Not adding up somehow…

So let’s look at what causes dyslexia when learning to read.

Before kids start school or pre-school, they don’t know anything about letters, the alphabet or reading.  Everything in their world is 3D.


If you say to your 3 year old, “Go and brush your teeth and put your pyjamas on”, they will get a visual image in their memory of a toothbrush and where that is and how to use it and anotherwhat_causes_dyslexia visual in their memory of their pyjamas and where they are and how to put them on.  It doesn’t matter if the toothbrush is in the cupboard or on the sink or in a cup, a toothbrush is a toothbrush – it’s 3D.  So they have visual memory of the objects (toothbrush and pyjamas) and experiential memory of how to use them.

When they start school or pre-school, they are introduced to letters and numbers.  Normally, the letters and numbers are 2D.  When we are dealing with 2D objects like the letter ‘b’, if it’s in a different position like the toothbrush, it will change its identity to a ‘d’.

I should say here that when it comes to letters, numbers and words, they have three parts.  What the letter looks like, ‘b’, what the name of the letter is, ‘be’, and what the letter represents, ‘bah’.

That sounds easy, right…wrong!

what causes dyslexia

In the English language there are 26 letters and numerous academics state that those 26 letters can represent between 44 and 174 sounds!  Yikes!

So when kids are learning the sounds of the letters, one letter can represent as many as 4 sounds.  Now that can be really confusing – especially if you’re only 5 years old!

If a child writes a letter and it’s backwards, like a ‘b’ instead of ‘d’ when they are first starting to learn how to write or read it, no dramas.  It will take them a couple of years to create the accurate memory of the letter and how it should look.  What I’m trying to say here is, developmentally its normal for children to write reversals up until they’re about 8 years old.  But if the child is put under pressure or develops fear around learning, they will stop trying and develop strategies or behaviours to cope with the pressure and anxiety they are feeling.

No. 2 – Confusion

So maybe the cause of dyslexia apart from genetics is confusion – about the 2D letters or numbers and what they mean.

No. 3 – Pressure

Maybe the confusion wouldn’t be so great if kids had time on their side.  But these days they don’t.  A lack of time to process creates pressure to perform.  By the end of a child’s first year of school, known as Foundation or Kindy, in the new National Curriculum they are expected to know their numbers up to 30 as well as the letters of the alphabet, upper and lower case and what sounds they represent.  They are also expected to know many sight words or ‘high frequency’ words and be able to construct simple sentences.  All of this only 12 months after being able to have a nap after lunch.  No time for napping at school.  Our little kids are under a lot of pressure to ‘get it’ and quick!

No. 4 – Visual Processing

So perhaps another cause of dyslexia apart from genetics and confusion is that they continue to prefer the visual processing they’ve been doing and not understanding or being able to process verbal thought like sounds.  They learn the rules like i before e except after c, but where does that leave them when they are trying to work our ‘weird’?  CONFUSED!

English is crazy – apart from 26 letters and at least 44 sounds, there are rules and exceptions to the rules (like in ‘weird’).  Dyslexia is about how our brain processes information, visually or verbally.  So if you’re a little kid who has the genetic disposition, enough pressure, anxiety and confusion, and you like to process visually, you’re going to develop dyslexia.


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[1] 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.

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