Expert: Ettina - 12/9/2009

Question
I am bipolar and my husband had ADD when he was young. I have 1 son who was born 6 weeks eairly and he was 6 lbs 1 oz and he has autism. What are the chances that my next baby will have autism?

Answer
Well, there's certainly a higher likelihood, but I can't tell you very exactly. Most studies have found that about 4-9% of siblings of autistic kids are also autistic, but that's combining a very diverse group of autistic kids, with different etiologies and genetic backgrounds and so forth, so for individual families it could vary quite a lot.
The fact that you and your husband both have conditions related to autism increases the probability of your second child being autistic. Although no studies that I know of have examined the probability of autism in children of parents with autism-related conditions, it's been found that many parents of autistic kids have some degree of autistic traits, and this is especially true for parents with more than one autistic child.
Siblings of autistic kids, even if they're not autistic, also are more likely to have autistic traits. This can show up in having conditions that overlap with autism or are genetically linked to autism (like you and your husband) or in having autistic traits that don't meet the severity needed for a diagnosis. Incidentally, this can be a positive thing, since many gifted kids have subclinical autistic traits (particularly obsessive interests) and it seems like siblings of autistic kids are more likely to be gifted.