By far, the exact cause of dyslexia still remains unknown. But researchers have found that the condition runs in families.
All the genetic links to dyslexia are not fully understood. However, studies do find that the condition is passed through families. For example, if one twin has dyslexia, it's very common for the other twin to have it as well.
In other words, how exactly the genes affect the brain is not clear. But one thing is clear: dyslexia is considered as a genetic and neurological condition, so it's not caused by a lack of intelligence.
Keyword: dyslexia hereditary