The exact cause of dyslexia is unknown. However, there is known to be a genetic factor and hereditary influence on dyslexia. Find out here if dyslexia is genetic.
Is Dyslexia Genetic or Hereditary?
Dyslexia often appears to run in families. It is thought that certain genes that someone inherits from their parents “may act together in a way that affects how some parts of the brain develop during early life.”
According to Nelson Dorta (PhD) for Understood.org, about 40% of siblings of children with dyslexia “also have reading issues.” 49% of parents of dyslexic children also have dyslexia. Despite these statistics, the exact ways that genetics lead to dyslexia are still not very well understood.
Many people think about genetics in terms of one gene being passed on from a parent to a child. Normally if a gene were associated with a condition, both the parent and the child would have that condition. With dyslexia however, there are multiple genes with differences, not just the one.
Both mothers and fathers can pass dyslexia on to their children if either parent has it. There is roughly a 50% – 60% chance of a child developing dyslexia if one of their parents has it.
“A few genes associated with dyslexia are on the X chromosome.” Females have 2 of these chromosomes while males have one X chromosome and one Y chromosome. Even though both genders have at least one X chromosome, dyslexia is more commonly diagnosed in males. The fact that both genders have at least one of these chromosomes is also why either the mother or the father can pass dyslexia onto their child.
According to an American study, the risk of a child developing dyslexia is increased from 4 times to 13 if one of their parents has a similar diagnosis.
Dr. Beve Hornsby found that 88% of dyslexics had a near relative who had similar issues with reading and spelling.
The Dyslexia Research Trust once conducted a study where they “collected nearly 400 families with at least 1 dyslexic child” in Oxford, U.K. The DRT “detected a strong signal (of dyslexia) on the short arm of chromosome 6,” whereas they located the strongest linkage on chromosome 18. The DRT also gathered similar findings in a second set of families they collected in the USA while another research group “confirmed the same chromosome 18 site in a set of families (they) collected in Australia.”
The name of the gene that is most likely to cause dyslexia is KIAA0319. It is strongly associated with chromosome 6 in people with dyslexia.
Many people believe that dyslexia runs in families. If a mother or a father has dyslexia, either of them can pass it on to their child. Children have a higher chance of developing dyslexia if at least one of their close relatives also has it.