Parents’ Autistic Traits and Their Infants’ Development: What the Data Really Says

Friday, October 10, 2025.

Autism runs in families — though not in the sense that Aunt Mildred’s devotion to organizing her spice rack means her baby will be scripting Finding Nemo at three.

What passes for “quirky” in one generation may simply be a gentler echo of inherited neurodivergence in the next.

But in the sense that autism is highly heritable. Twin studies have been saying this for decades (Tick et al., 2016).

Now, a massive new study out of Japan adds more detail.

The Japan Environment and Children’s Study (JECS)—a sample so large it makes most developmental research look like a parish bake sale—has found that parents with stronger autistic traits are more likely to have infants who show developmental difficulties.

That’s true for mothers and fathers, though not always in the same way (Hirokawa et al., 2025).

What the Study Found

JECS followed more than 31,000 mother–father pairs who signed on during pregnancy. Parents filled out the Autism Spectrum Quotient (Baron-Cohen et al., 2001), and their babies were assessed with the Ages & Stages Questionnaire at 6 and 12 months.

Here’s the gist:

• Mothers’ autistic traits were linked to developmental difficulties at both 6 and 12 months.

• Fathers’ autistic traits showed up at 12 months—but mostly in girls.

• Across the board, boys had more difficulties than girls, a finding consistent with autism’s well-established sex differences (Loomes et al., 2017).

In short: having higher levels of autistic traits—even without a diagnosis—was associated with more developmental challenges in babies during the first year of life.

The Broader Autism Phenotype

This isn’t just about autism itself.

Psychologists talk about the Broader Autism Phenotype (BAP)—traits like rigidity in routines, unusual communication styles, or a hyper-focus on details.

These don’t warrant a diagnosis, but they can shape parenting and family life (Piven & Palmer, 1999).

Think of BAP as the grayscale shading around the sharper lines of autism.

Hirokawa’s study suggests these subtler traits may show up in infants’ development earlier than many parents expect.

Case Vignette #1: The Routine Dad

Mark thrives on predictability. Dinner at 6:00, baby bath at 6:30, lights out at 7:00—his phone alarm buzzes like a NASA countdown.

His daughter, however, experiments with chaos: babbling at midnight, protesting every transition. Mark’s structure keeps the household running, but it also sharpens his perception of her “difficulties.”

When every deviation from schedule feels like turbulence, developmental bumps are harder to smooth over.

The Question of Bias

Of course, we should be cautious. Parents reported both their own traits and their children’s difficulties.

That opens the door to reporting bias. A detail-oriented, socially vigilant parent may notice and log every quirk. Their neighbor might shrug and think a missed milestone just means “he’ll talk when he’s ready.”

Case Vignette #2: The Detail-Focused Mom

Leah prides herself on noticing small things—misplaced commas, crooked picture frames.

At six months, her son doesn’t clap during peekaboo. She flags it as a developmental delay.

At the next checkup, he’s clapping just fine—just not for peekaboo. Only for the dog. Leah’s sensitivity makes her an excellent advocate, but it also means she may report concerns sooner, and more often, than other parents.

Why This Matters

The point here isn’t guilt. It’s foresight.

If autism runs in families, and subtle parental traits influence early child outcomes, then screening and support can start earlier and be tailored more thoughtfully.

Other studies show that early identification and intervention can improve developmental trajectories for children at high likelihood of autism (Estes et al., 2015; Green et al., 2017).

In other words, knowing these connections helps families get ahead of the curve.

FAQ: Parents’ Autistic Traits and Child Development

Does having autistic traits mean my child will definitely be autistic?
No. Genetics are powerful, but not destiny. Many children of autistic parents—or parents with subtler autistic traits—are not autistic themselves. This is about likelihood, not inevitability.

Are fathers’ traits less important than mothers’?
Not exactly. In this study, maternal traits predicted difficulties at both 6 and 12 months. Paternal traits only showed up at 12 months—and mainly in girls. Timing and expression may differ, but both matter.

What exactly is the “Broader Autism Phenotype”?
Traits like rigid routines, unusual communication styles, or a heightened eye for detail. Not diagnostic, but still influential.

Should I worry if I see delays in my baby?
Don’t panic. Monitor, yes. Worry, no. Many so-called “delays” resolve with time, but early screenings are always a good idea. Early intervention works best when it starts early (Estes et al., 2015; Green et al., 2017).

How do I support my child if I have autistic traits myself?
Use your strengths. A parent who loves structure can create predictability.

A detail-focused parent may notice subtle shifts that others miss. Where challenges arise—like social play—external supports such as speech therapy, occupational therapy, or parent-mediated interventions can fill the gap.

People Also Ask: Autism, Parents, and Early Development

Can autism be detected at 6 months?
Not formally. At six months, clinicians can see risk markers—like reduced eye contact or unusual motor patterns—but autism isn’t diagnosed until 18–24 months (Zwaigenbaum et al., 2015).

Do autistic parents raise autistic children?
Sometimes. Children of autistic parents are at higher risk of autism or elevated traits (Yip et al., 2022). But a “higher risk” is not necessarily a “guaranteed outcome.”

Is autism always genetic?
No, not always. Genetics explain much of autism’s likelihood, but environment—parental age, prenatal factors, birth complications—interacts with genes in complex ways.

What’s the difference between autistic traits and autism?
Traits can exist without clinical impact. Autism, as a diagnosis, requires traits that significantly affect daily functioning (American Psychiatric Association, 2013).

Can early intervention change outcomes?
Yes. Parent-mediated interventions have been shown to improve language, social skills, and developmental trajectories (Green et al., 2017).

What Parents Can Take From This (Without Spiraling)

If you’re a parent reading this and mentally replaying every time you alphabetized the spice rack instead of chatting at preschool pickup, relax.

Having autistic traits does not mean your child is doomed.

It may mean you notice differences earlier, interpret them through your own lens, and sometimes need extra scaffolding for yourself and your child.

Therapists see this all the time: a parent who dislikes small talk notices their toddler isn’t babbling as expected. A dad who thrives on structure notices his child resists transitions. These insights are useful if met with support instead of shame.

Developmental differences are not failures. They’re signals.

Signals that can be met with resources—speech therapy, occupational therapy, parent coaching. More importantly, they can be met with compassion.

Families who understand their own patterns, whether that’s autism, anxiety, or just a preference for quiet dinners, are better equipped to support their children without drowning in guilt.

If you’re a parent with a few autistic traits, take heart: you may be the best person to understand and advocate for your child.

This research isn’t about blame—it’s about giving families a head start.

Be Well, Stay Kind, and Godspeed.

REFERENCES:

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Washington, DC: Author.

Baron-Cohen, S., Wheelwright, S., Skinner, R., Martin, J., & Clubley, E. (2001). The Autism Spectrum Quotient (AQ): Evidence from Asperger syndrome/high-functioning autism, males and females, scientists and mathematicians. Journal of Autism and Developmental Disorders, 31(1), 5–17. https://doi.org/10.1023/A:1005653411471

Estes, A., Munson, J., Rogers, S. J., Greenson, J., Winter, J., & Dawson, G. (2015). Long-term outcomes of early intervention in 6-year-old children with autism spectrum disorder. Journal of the American Academy of Child & Adolescent Psychiatry, 54(7), 580–587. https://doi.org/10.1016/j.jaac.2015.04.005

Green, J., Pickles, A., Pasco, G., Bedford, R., Wan, M. W., Elsabbagh, M., ... & Johnson, M. H. (2017). Randomised trial of a parent-mediated intervention for infants at high risk for autism: Long-term outcomes to age 3 years. Journal of Child Psychology and Psychiatry, 58(12), 1330–1340. https://doi.org/10.1111/jcpp.12728

Hirokawa, K., Baba, S., Ikehara, S., Cui, M., Kitano, N., Nakayama, H., Ozono, K., Iso, H., & Japan Environment and Children’s Study Group. (2025). Associations between parents’ broader autism phenotype and children’s developmental difficulty scores at 6 and 12 months: A prospective study. International Journal of Behavioral Development.

Loomes, R., Hull, L., & Mandy, W. P. (2017). What is the male-to-female ratio in autism spectrum disorder? A systematic review and meta-analysis. Journal of the American Academy of Child & Adolescent Psychiatry, 56(6), 466–474. https://doi.org/10.1016/j.jaac.2017.03.013

Piven, J., & Palmer, P. (1999). Cognitive deficits in parents from multiple-incidence autism families. Journal of Child Psychology and Psychiatry, 40(5), 733–744. https://doi.org/10.1111/1469-7610.00489

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

Yip, B. H., Bai, D., Mahjani, B., Klei, L., Pawitan, Y., Hultman, C. M., ... & Sandin, S. (2022). Heritable and shared genetic contributions to autism spectrum disorder in a population-based sample of twins and their families. JAMA Psychiatry, 79(3), 234–242. https://doi.org/10.1001/jamapsychiatry.2021.3790

Zwaigenbaum, L., Bauman, M. L., Choueiri, R., Kasari, C., Carter, A., Stone, W. L., ... & Natowicz, M. R. (2015). Early identification and interventions for autism spectrum disorder: Executive summary. Pediatrics, 136(Suppl 1), S1–S9. https://doi.org/10.1542/peds.2014-3667B