If a sibling has autism, there is a high chance another sibling will have it too. What does this imply about familial risk?

• A. There Is a High Chance Another Sibling Will Have It
• B. No Increased Risk for Siblings
• C. Autism Is Caused by Vaccines
• D. The Risk Is Unpredictable

Answer: (A)

The main idea here is familial or genetic risk: autism tends to run in families, so if one sibling is affected, the chance that another sibling will be affected is higher than in the general population. This reflects inherited susceptibility—siblings share a good portion of their genes, and certain genetic factors raise autism risk. It’s not a certainty, because many genes and environmental influences contribute, but the recurrence risk within a family is clearly elevated. This has nothing to do with vaccines. In practice, recognizing the increased familial risk supports closer developmental monitoring of siblings and, when appropriate, genetic counseling.