Key Highlights
- Autism has a strong genetic basis, but there is no single “autism gene.”
- Both mothers and fathers can pass on genetic variations linked to autism.
- Research points to a slightly stronger paternal influence, especially with advanced father’s age.
- Many autism cases involve spontaneous (de novo) mutations that aren’t inherited from either parent.
- Maternal health, pregnancy environment, and other environmental factors interact with genetics.
- Understanding autism genetics can help families move from blame to informed support.
When a child is diagnosed with autism, parents often find themselves lying awake at night, replaying questions in their minds: Did this come from me? Did I miss something? Could I have prevented it?
It’s completely natural to wonder how autism develops and whether it came from the mother or father. But the reality is more nuanced than pointing to one parent or one gene. Autism is shaped by a combination of genetic influences, spontaneous changes in DNA, and environmental factors.
This article walks you through what we currently know about autism genetics, how inheritance works, why both parents are involved, and why the story is much more complex — and more hopeful — than simply asking, “Whose side did it come from?”
What Is Autism Spectrum Disorder?
Before we dive into inheritance patterns, it helps to understand what autism actually is on a biological level.
Autism spectrum disorder (ASD) is a neurodevelopmental condition. That means it affects how the brain develops, processes information, and connects different areas responsible for communication, social interaction, flexibility, and behavior.
Some autistic individuals may have noticeable challenges with social cues or changes in routine. Others might have intense interests, strong attention to detail, or unique learning styles. This is why we call it a spectrum — the range of traits and support needs is wide.
Core Features of Autism
While every autistic person is different, some common areas of difference include:
- Social communication and interaction
- Sensory processing (being more or less sensitive to sounds, lights, textures, etc.)
- Repetitive behaviors or routines
- Strong, focused interests
These traits do not appear out of nowhere. They are shaped by brain development — and brain development is influenced, in part, by genetics.
How Genetics Influence Autism
We now know that autism has a strong genetic component. That doesn’t mean there is a single “autism gene” that flips on and off. Instead, many different genes each contribute a small amount to overall autism risk.
Think of it like a recipe: no single ingredient makes a dish, but the combination and proportions of ingredients determine the final result. With autism, the “ingredients” are many genes that work together (or sometimes disrupt one another) during brain development.
Genes and Brain Development
Many autism-associated genes are involved in:
- How brain cells (neurons) form connections
- How messages are sent between neurons
- How the brain organizes itself during pregnancy and early childhood
Changes in these genes may influence the way information is handled in the brain. That doesn’t mean “broken” — it means different wiring, which leads to different ways of experiencing the world.
What Does Heritability Mean in Autism?
You’ll often hear scientists say that autism is “highly heritable.” Heritability is a statistical term, not a guarantee. It refers to how much of the variation in a trait across a population can be explained by genetic differences.
For autism, heritability is estimated to be around 40–80%. In simple terms, genetics play a large role in whether someone is autistic — but they’re not the only piece of the puzzle.
Does Autism Come More from the Mother or Father?
This is the question that worries many families: who carries the autism gene, mother or father?
- Both parents contribute half of their child’s DNA.
- Both can carry and pass along autism-related genetic variants.
- Recent research suggests that new genetic mutations (de novo mutations) are slightly more likely to come from the father, especially as paternal age increases.
However, that doesn’t mean the father is “more responsible” or that the mother plays a minor role. Maternal genetics, maternal health, and prenatal environment can all significantly shape how those genes are expressed. Autism is not a one-parent story; it is shared, layered, and complex.
Types of Genetic Variations Linked to Autism
Not all genetic changes are created equal. Some are big, some are small, some are inherited, and some are brand new in the child.
Common Types of Genetic Variations
- Copy Number Variations (CNVs)
These are sections of DNA that are deleted or duplicated. Even small changes in the number of copies of certain genes can affect brain development. - Single-Gene Mutations
This is a change in a single gene that can have a strong effect on neural function. In some families, a rare mutation in one specific gene can contribute heavily to autism traits. - De Novo (Spontaneous) Mutations
These are new genetic changes that appear in the child but are not found in either parent’s DNA. They arise spontaneously in sperm, egg, or early embryonic cells. - Polygenic Risk
Often, there is no single big mutation. Instead, hundreds of small genetic differences add up to increase the likelihood of autism. This polygenic pattern explains why traits can be subtle in parents but more pronounced in a child.
Well-Known Autism-Related Genes and Their Roles
Researchers have identified several genes that consistently show up in autism studies. These don’t cause autism on their own but are associated with increased likelihood when altered.
| Gene | What It Does in the Body |
| SHANK3 | Helps build and maintain synapses, the connections between neurons. |
| ADNP | Acts as a “master regulator” controlling many other genes involved in brain development. |
| CHD8 | Influences how DNA is packaged, affecting which genes are turned on or off in brain cells. |
| SYNGAP1 | Important for synapse development, learning, and memory. |
These genes highlight just how fundamental brain development is to autism — and how small changes during early development can have lasting effects.
Spontaneous (De Novo) Mutations and Autism
One of the most important pieces of modern autism research is the role of de novo mutations. These are brand new changes in DNA that weren’t present in either parent’s genetic material.
They can occur:
- In the father’s sperm or the mother’s egg
- In the earliest cell divisions after conception
Because de novo mutations are new, they explain why autism sometimes appears “out of the blue,” even in families with no known history. Studies suggest that in families where only one child is on the spectrum, de novo mutations are often a significant part of the picture.
This is also where paternal age comes in: the older a father is, the more times his sperm cells have divided over his lifetime, and the more chances there have been for small copying errors in DNA.
How Autism Can Run in Families
If de novo mutations can cause autism, how do we also see autism “run in families”? The answer is that both inherited variants and new mutations are involved.
Polygenic Inheritance: Many Small Pieces
Autism risk is often polygenic. That means:
- A parent can carry multiple autism-related variants without being autistic.
- If the other parent also carries some, the combination in the child might cross the threshold where autism traits become more noticeable.
- Different siblings can inherit different combinations of these variants, which is why one child may be autistic and another may not — or why their support needs might be very different.
This is why family trees of autistic individuals can look scattered: one uncle, a distant cousin, a sibling — and sometimes no obvious pattern at all.
Maternal vs. Paternal Genetic Influence
Now, back to the key question: who carries the autism gene, mother or father? The honest answer is: both, just in different ways.
Maternal Influence
On the maternal side:
- Mothers contribute half their child’s DNA.
- Some autism-associated gene variants have been studied more closely in mothers, partly because of the way they may interact with pregnancy and development.
- Maternal health during pregnancy — such as infections, metabolic conditions, or exposure to certain substances — can work together with genetic risk to influence outcomes.
Paternal Influence
On the paternal side:
- Fathers also contribute half of the child’s DNA.
- De novo mutations are more likely to originate in sperm, and the rate of these mutations increases with age.
- Some studies suggest that when siblings with autism are compared, they sometimes share more genetic material from their father than their mother, hinting at a slightly stronger paternal contribution in some families.
However, this does not mean fathers are “to blame.” It simply reflects how human biology and cell division work over time.
The Female Protective Effect
One theory that helps explain both autism’s higher diagnosis rate in males and the complexity of inheritance is the female protective effect.
This idea suggests:
- Females may have a higher threshold for showing autistic traits.
- They might need more or stronger genetic risk factors than males to receive an autism diagnosis.
- Because of this, a mother can carry several autism-associated variants without meeting criteria for autism herself.
In practice, that means a mother could be a “carrier” of multiple risk genes and pass them on. A son who inherits those same genes might show more noticeable traits because he doesn’t have the same biological protective effect.
The Role of Environment Alongside Genetics
Genes set the stage, but environment influences how the play unfolds. While autism is strongly influenced by genetics, environmental factors can shape how those genetic instructions are carried out during development.
Examples of Environmental Factors Studied in Autism
Scientists have explored links between autism risk and:
- Certain prenatal infections
- Maternal health conditions like diabetes or obesity
- Severe birth complications or lack of oxygen
- Exposure to some medications or toxins during pregnancy
- Advanced parental age
Most of these factors, if they have an effect, likely work by interacting with existing genetic risk instead of causing autism on their own. It’s not one thing; it’s many small things combining over time.
Can Genetic Testing Show Which Parent Carried the Autism Gene?
Genetic testing can sometimes identify specific gene variants, chromosomal changes, or de novo mutations associated with autism. But it has limits.
- In many cases, testing reveals a genetic variant but still can’t say exactly where it came from without testing both parents.
- Even when a variant is found, it usually doesn’t explain the whole story — it’s just one piece of a larger puzzle.
- For many families, no clear genetic cause is identified, even though autism is clearly present.
Genetic testing can be helpful for understanding medical risks, accessing certain supports, or guiding family planning decisions, but it rarely provides a simple answer like, “It came from mom,” or “It came from dad.”
Common Myths About Autism Genetics
Because this topic is emotional and complex, a lot of myths float around. Here are a few to clear up:
Myth 1: “Autism is caused by bad parenting.”
Autism is not caused by parenting style, lack of affection, or anything a parent did “wrong.” It is a neurodevelopmental condition with a strong biological and genetic basis.
Myth 2: “If neither parent is autistic, autism can’t be genetic.”
Even when parents are not autistic, they can carry genetic variants that increase risk, or their child can have de novo mutations. Genetics can still be involved even without obvious family history.
Myth 3: “One parent is to blame.”
Science does not support blaming one parent. Both contribute genetic material, and many cases involve brand new mutations that neither parent had any control over.
Supporting Your Child, Regardless of Genetics
Understanding autism genetics can answer some important questions — but it doesn’t change who your child is or what they need today. Whether autism risk came from the mother, father, both, or neither in a straightforward way, your child is still the same unique, capable person they were before you learned any of this.
What matters most is:
- Early support
- Compassionate understanding
- Access to services that build communication, independence, and daily living skills
This is where high-quality, individualized ABA therapy can make a meaningful difference.
Conclusion
So, who carries the autism gene — mother or father? The most accurate answer is: both, in different ways, and sometimes neither in a direct, inherited sense. Autism arises from a complex tapestry of genetic variations, spontaneous mutations, and environmental influences. It does not come down to one parent, one gene, or one moment.
At Little Champs ABA, we meet families every day who are processing these questions. Our focus is not on blame, but on support. We care deeply about helping children on the autism spectrum build practical skills, emotional resilience, and confidence — regardless of how or why autism came into the picture.
We proudly provide ABA therapy services across Colorado and Utah, offering flexible options to meet families where they are:
- ABA therapy at home – individualized one-on-one support in your child’s familiar environment.
- ABA therapy in school – collaboration with teachers and school teams to promote learning and positive behavior.
- ABA therapy in daycare – early intervention woven into natural play and daily routines.
- ABA therapy for teenagers – focused on independence, social skills, executive functioning, and life readiness.
- Telehealth ABA – convenient, flexible services delivered virtually to fit your family’s schedule.
As a team, we believe every child deserves the chance to grow, learn, and feel understood. Genetics may help explain whyautism happens, but they don’t define your child’s potential.
If you’re ready to explore support options or simply have questions, we’re here to walk this journey with you.
Learn more or get started at Little Champs ABA.
Frequently Asked Questions
Can genetic testing tell me which parent my child’s autism came from?
Genetic testing can sometimes identify variants associated with autism, but it usually can’t definitively say which parent they came from without testing both parents — and even then, it rarely tells the whole story.
If neither parent is autistic, how can my child be on the spectrum?
Autism can result from a mix of subtle inherited variants and new (de novo) mutations that weren’t present in either parent. So a child can absolutely be autistic even if both parents are neurotypical.
Can autism skip a generation?
Because autism risk is made up of many small genetic contributions, it can appear to “skip” generations. Family members may carry risk variants without being diagnosed, and then a child may inherit a combination that crosses the threshold for autism.
Is one parent more likely to “carry” autism?
Both parents can carry and pass on autism-related genes. Some studies show more new mutations from the father’s side, especially with older paternal age, while theories like the female protective effect highlight a complex role for maternal genetics. Neither parent is solely responsible.
Sources:
- https://www.bbc.com/future/article/20250415-the-genetic-mystery-of-why-some-people-develop-autism
- https://www.autismspeaks.org/what-causes-autism
- https://medschool.ucla.edu/news-article/is-autism-genetic
- https://www.simonsfoundation.org/2025/07/09/new-study-reveals-subclasses-of-autism-by-linking-traits-to-genetics/
- https://research.childrenshospital.org/research-units/genetics-and-genomics-research/genetics-and-genomics-stories/autism
- https://my.clevelandclinic.org/health/articles/autism
- https://www.uclahealth.org/news/release/new-genetic-clues-uncovered-largest-study-families-with