Heritability: The Genetic Ripple Effect of Neurodiversity
- 4 days ago
- 4 min read
By Harry Motro Clinical Director, Neurodiverse Couples Counseling Centerc
Does autism run in families
Why Neurodiversity So Often Shows Up All Over One Family Tree
A lot of families walk into an evaluation thinking they’re dealing with one person’s brain.
Then the diagnosis lands—autism, ADHD, or AuDHD—and it’s like someone turned the lights on.
A parent reads the traits and thinks, “That’s me.”
Then they think about a sibling.
Then a grandparent.
Then the “eccentric” aunt or uncle everyone has always tiptoed around.
That moment is real.
And it’s not just your imagination.
Neurodivergent traits often cluster in families because both autism and ADHD show strong genetic influence in research.
This is what we call the Genetic Ripple Effect: one diagnosis becomes a window into the whole family’s wiring.
What those percentages actually mean
Let’s translate the science into normal language—without turning it into fate.
1) Heritability ≠ “I passed down 70% of this”
When you hear “ADHD is ~70–80% heritable,” it doesn’t mean there’s a 70–80% chance a parent “gave” ADHD to a child.
Heritability is a population-level statistic.
It means that, across a population, a large portion of the differences we see in ADHD traits are associated with genetic differences.
It says nothing about any one individual’s destiny.
But it does mean this:
If ADHD is present in your child, it’s very common to find ADHD traits in one or both parents—diagnosed or not. In one major review, the average heritability across twin studies is about 74%.
2) Autism also shows substantial heritability
Autism heritability estimates vary by study design and assumptions, but meta-analytic work finds substantial heritability, with estimates reported in the 64–91% range.
Again: not destiny.
But it strongly supports why families often recognize patterns across generations once they know what to look for.
Why AuDHD makes families feel “pulled in two directions”
The graphic highlights co-occurrence (AuDHD overlap). That matters because it changes how a person can look day-to-day.
A recent review describes the prevalence of ADHD in autistic individuals as often ranging roughly 50–70% in meta-analytic findings.
What that can look like at home:
A strong need for sameness and a strong need for stimulation
A child who craves routine and gets bored instantly
“Focused” in one moment, “scattered” the next
“Rigid” under stress, but also “impulsive” under stress
Families often feel confused because they’re trying to use one explanation, and the child is living with more than one neurological pull.
The sibling shift: why the “baseline” stops applying
The graphic shows a general-population baseline at the bottom and a jump in probability for siblings.
That jump is real.
A major 2024 recurrence study reported that about 20.2% of younger siblings developed autism when they had an older autistic sibling.
That’s not “most siblings,” but it’s high enough that families often look back and realize, “Oh… we missed signs in the other kid too.”
Even when a sibling doesn’t meet criteria for a diagnosis, many families still notice shared traits—sensory differences, processing differences, emotional intensity, attention patterns—which can shape the whole household.
The “Broader Phenotype”: why relatives can look familiar without fitting the diagnosis
One reason neurodiversity feels “everywhere” is that not everyone has the same presentation.
Researchers describe a broader autism phenotype—relatives who don’t meet full diagnostic criteria but show recognizable traits (communication style, rigidity, detail focus, sensory sensitivity, social differences).
So the family tree can include:
People with clear diagnoses
People with subclinical traits
People who masked for decades
People who were simply labeled “difficult,” “cold,” “controlling,” “too sensitive,” or “lazy”
And once those labels are in place, the family story can turn toxic fast.
Because “difference” gets treated like a character flaw.
Why this matters emotionally (and why it can be a relief)
When families understand the Genetic Ripple Effect, two things usually happen:
Shame drops. The story changes from “What’s wrong with us?” to “Oh—this is a wiring pattern.”
Blame gets exposed as lazy storytelling.
“Selfish” becomes “overloaded.”
“Defiant” becomes “stuck.”
“Controlling” becomes “trying to stay regulated.”
“Lazy” becomes “executive function collapse.”
That doesn’t excuse harm.
It just replaces moral judgment with accuracy—which is the only place real change starts.
How Family Therapy helps
When neurodivergence clusters in a family, the stress rarely lives inside one person—it lives between people. That’s why families often need a coordinated family approach, not just individual work.
If you want the how—how we actually structure this clinically—read Blog 1: Integrated Neurodiverse Family Therapy
Harry Motro
Clinical Director, Neurodiverse Couples Counseling Center
© 2025 New Path Family of Therapy Centers Inc. All rights reserved. No portion of these statements may be reproduced, redistributed, or used in any form without explicit written permission from the New Path Family of Therapy Centers.
Want to learn more about yourself?
Explore our sister site, Adult Autism Assessment, and take a deeper dive into your journey of self-discovery. Click the links below to get started!
Resources & Further Reading
Faraone, S. V., & Larsson, H. (2019). Genetics of attention deficit hyperactivity disorder. Molecular Psychiatry, 24(4), 562–575. https://doi.org/10.1038/s41380-018-0070-0
Grønborg, T. K., Schendel, D. E., & Parner, E. T. (2013). Recurrence of autism spectrum disorders in full- and half-siblings and trends over time: A population-based cohort study. JAMA Pediatrics, 167(10), 947–953. https://doi.org/10.1001/jamapediatrics.2013.2259
Hansen, S. N., Schendel, D. E., Francis, R. W., Windham, G. C., Bresnahan, M., Levine, S. Z., … Parner, E. T. (2019). Recurrence risk of autism in siblings and cousins: A multinational, population-based study. Journal of the American Academy of Child & Adolescent Psychiatry, 58(9), 866–875. https://doi.org/10.1016/j.jaac.2018.11.017
Ozonoff, S., Young, G. S., Bradshaw, J., Charman, T., Chawarska, K., Iverson, J. M., Klaiman, C., Landa, R. J., McDonald, N., Messinger, D., Schmidt, R. J., Wilkinson, C. L., & Zwaigenbaum, L. (2024). Familial recurrence of autism: Updates from the Baby Siblings Research Consortium. Pediatrics, 154(2), e2023065297. https://doi.org/10.1542/peds.2023-065297
Sandin, S., Lichtenstein, P., Kuja-Halkola, R., Larsson, H., Hultman, C. M., & Reichenberg, A. (2014). The familial risk of autism. JAMA, 311(17), 1770–1777. https://doi.org/10.1001/jama.2014.4144
Thapar, A., & Cooper, M. (2016). Attention deficit hyperactivity disorder. The Lancet, 387(10024), 1240–1250. https://doi.org/10.1016/S0140-6736(15)00238-X
Tick, B., Bolton, P., Happé, F., Rutter, M., & Rijsdijk, F. (2016). Heritability of autism spectrum disorders: A meta-analysis of twin studies. Journal of Child Psychology and Psychiatry, 57(5), 585–595. https://doi.org/10.1111/jcpp.12499
Comments