Is dyslexia genetic?

Parents often ask me this question. The simple answer is yes, dyslexia is genetic. But genetics is a complex issue. So, it’s important to understand how it works.

First, it’s clear that there is a hereditary aspect of dyslexia because it runs in families. About 40 percent of siblings of kids with dyslexia also have reading challenges. And as many 49 percent of their parents do, too. The exact way genetics leads to dyslexia is still not well understood, however.

People often think about genetics in terms of one gene being passed down from parent to child. If a gene were associated with a condition, both parent and child would have that condition. But with dyslexia, there are multiple genes with differences, not just one.

These particular genes impact a process that forms connections across the brain. In people with dyslexia, this process is organized differently. Researchers believe this affects the ability to read.

Genetics isn’t the only factor that determines a child’s ability to read, however. Environment also plays a role. Quality of reading instruction can have a huge impact on all kids. But it’s especially true for kids who are more likely to have dyslexia. They need high-quality instruction early on.

Studies on twins have shown that reading disorder is 60 to 70 percent due to genes. But it’s about 30 percent due to environment. Environment plays an even larger role in kids who grow up in poverty or with parents who are less educated.

So, to get back to your question, yes, dyslexia is “genetic.” And if you have one child with dyslexia, your other children are more likely to have it. Looking for signs of early reading problems can allow you to intervene as soon as possible. Having good reading instruction makes a big difference in reading success.

Watch an expert explain more about dyslexia and the brain.