What can I do if my husband brother is autistic. How big is the chance for us to have a child with autism?

See below. Some litature states it is genetic. However, the chance is increased but only slightly. (very small).
Somewhat. Incidence of autism increases with positive family history. The risk is slightly higher than 1%, as seen in the general population.
Increases. Because there does appear to be a genetic connection with autism, the risk goes up if another member of the family has been diagnosed with it if there are family members with autoimmune diseases.