A new study published online Monday in Pediatrics, shows nearly one in five children with an autistic older sibling will develop the disorder, too. Researchers observed 664 infants with at least one older autistic sibling.  About 19-percent ended up with an autism diagnosis by their third birthday.  Children with more than one older autistic sibling had a higher chance of also being autistic.

If you don't know much about autism, there is no proven cause.  However, experts believe genetics and external influences are contributing factors.  Examples of external influences would be infections, pollution and other non-inherited problems.  Autism is proven to be more common in boys.  In regards to this most recent study, mong the siblings that developed autism, 26 percent were boys while 9 percent were girls.

More information on autism can be found at KidsHealth.org.