Cluttering has a clear hereditary component. About 85-90% of the cluttering speakers have a family member with a congenital fluency disorder, such as cluttering or stuttering.
Relations with other conditions
Scientific research shows that cluttering has strong correlations with, among other disorders, learning difficulties and ADHD. In people with these conditions cluttering exists more than averagely. To be clear, this does not mean that if you clutter you will have learning difficulties or ADHD per se. Cluttering and other related disorders can easily exist separately.
Do not confuse with…
Cluttering should not be confused with a language development disorder (LDD). People with a language development disorder also have problems with planning their language at a lower speech rate. For that same reason, cluttering also should not be seen as an articulation defect: people with this condition also experience articulation problems at a low rate of speech.