There are parents who have many autistic children.
Once I saw a Facebook post by a mom to five autistic children – all biologically hers.
I have a clinical diagnosis of Autism Spectrum Disorder.
I have a brother whom other family members are convinced is autistic as well.
There’s six of us siblings total. So two out of six are autistic.
This may seem like a lot, but it’s actually nothing compared to the many families out there with four or more autistic kids.
The Odds that a Sibling Will Be Autistic
When a family has one child with autism, what are the odds that another child will also be autistic?
Numerous studies show that autism occurs in families already with autism at substantially higher rates than in the general population.
This doesn’t mean it’s not possible for a neurotypical couple to produce an autistic child.
It also doesn’t mean that an autistic couple can’t have an NT child.
While rates vary depending on study design, high quality research places the recurrence risk between roughly 10% and 25%
A landmark California cohort study of 6,616 full siblings (born between 1990 and 2003) found a 10.1% recurrence risk, compared to just 0.52% in control siblings (American Journal of Psychiatry, Risch, et al).
This study suggests that having an autistic older child raises the sibling’s odds of being autistic almost 20-fold.
A Danish population study (1980-2004 births) published in JAMA Pediatrics (Hansen, et al) reported a relative recurrence risk of approximately 6.9 for full siblings, with maternal half‑siblings at 2.4 and paternal half‑siblings at 1.5, affirming the strong genetic component.
These two studies are among numerous that show a strong familial correlation when it comes to ASD.
Many people already know that autism “runs in families.”
If you regularly visit Facebook groups with a dedication to autism, it won’t be long before you see a post by someone who has at least three kids on the Spectrum.
It’s actually not all that uncommon, at least based on the Facebook autism community groups I regularly visit.
“I have three kiddos on the Spectrum” isn’t exactly ultra-unusual to see posted.
Nobody ever posts surprise over these mentions.
If one parent is autistic, this boosts the chances they’ll have at least one autistic child.
If both parents are on the Spectrum, this really drives up the odds.
As for the presentations of autism among several siblings who have this neurotype, it can be a good mix.
One may be minimal support needs (“mild” autism), while the other two might be high support needs.
Or, two might be “mid-support needs” while the third has profound autism.
It’s also possible that out of five kids, three have autism, and a fourth actually has it but nobody suspects it because the three have a more severe presentation – and that fourth has a more subtle presentation (minimal support needs or Level 1).
I’ve come across cases on Facebook in which the mom says she’s having her older child assessed for autism after two younger ones just got diagnosed.
- Nobody knows what percentage of the population has three (or four, or five or six) autistic kids.
- Nobody knows what the most number of autistic kids biologically to a single couple is.
- It’s logical to conclude that the more autistic kids born to a particular couple, the more total children they have.
It is so very fascinating to wonder how many kids would turn out autistic if a dual-autistic couple had 12 children!
Lorra Garrick has been covering medical and fitness topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer. In 2022 she received a diagnosis of Level 1 Autism Spectrum Disorder.
.
