Is autism really 'in the genes'?
Is vegan food safe for pregnancy? Here's what the research says
Back in the year 2015, about 1 in 150 Australians were diagnosed with autism. By 2018, that number had risen to 1 in 100, with 205,200 individuals officially on the spectrum. That's a staggering 25.1% increase in just three years.
According to the Australian Bureau of Statistics, there were 290,900 (1.1%) Autistic Australians in 2022, an increase of almost 41.8% from 2018.
So, what’s happening? Is autism becoming more common? Or are we simply becoming better at recognising and diagnosing it?
More importantly, can we take measures to prevent our kids from developing autism? Or are we, knowingly or unknowingly, contributing to it?
For a parent whose child has just been diagnosed with autism, one tiny question often lingers, nagging them: Did my child inherit this autism gene from me?
Blame or biology? The truth about autism inheritance
The science of autism’s genetic inheritance is complex, but understanding it is deeply personal, especially for parents searching for answers.
It becomes even more critical for families wanting to support their loved ones or understand the implications these discoveries may have on their future generation ‘if’ they carry the trait.
Understanding autism
As autism spectrum disorder (ASD) diagnoses have risen significantly in Australia, communities, caregivers and autism researchers have struggled to find answers.
Research indicates that genetic factors contribute significantly to autism spectrum disorder, with heritability estimates ranging from 40% to 80%.
Some studies have identified numerous gene variations associated with increased autism risk, highlighting the complex genetic landscape of the disorder.
But beyond the risk of developing autism, some studies find that parents may also pass on ‘traits’ linked to autism.
Sign up
Get tailored content based on your week of pregnancy
By signing up, you agree to receiving our Newsletters. Cancel anytime.
The complex genetic factors involved
Parents often worry that perhaps it was something that they did during pregnancy that may have caused their child’s autism.
And while the environment is known to play a role (we discuss that below), the majority of research indicates that genetics are the real MVP when it comes to autism spectrum disorder (ASD). We now know that the causes of autism spectrum disorder are manifold and dynamic! That means autism is not your average classic unicellular gene that’s causing different types of autistic conditions.
(Think of it like this: autism isn’t caused by one single “rogue” gene – it’s more of a team effort, with multiple genes working together in complex ways. Yes, with a plan and everything!)
Plus, if autism runs in the family, it’s so not a coincidence! (You know how they say, lightning never strikes twice in the same place!)
So, when more than one child in a family is diagnosed, it’s a BIG clue that genes are in the driver’s seat!
And now, thanks to advancements in genetic testing, scientists are starting to decode which genes are calling the shots.
Who carries the autism gene - mother or father?
Well, the verdict isn’t out yet! Both parents can carry genes linked to autism, though recent studies do suggest the paternal genome may play a bigger role.
But let’s break it down further.
Suspect 1: De Novo Mutations
Aside from inherited genetic risk factors, spontaneous mutations play a major role in developing autism.
De novo mutations, also known as new mutations, are genetic changes that appear for the first time in an individual and are not present in either parent’s DNA.
However, some studies do find that these mutations tend to increase with paternal age, leading some autism researchers to highlight the father’s contribution. It’s important to note that these mutations occur randomly and are not inherited from either parent!
What are the odds?
Well, based on this study, in low-risk families, it’s 52-67% and 30–39% of cases of all autism.
Suspect 2: DDX53 (Yes, it’s a gene, not a typo!)
Research has uncovered that specific genes play critical roles in brain development and may influence the inheritance of certain autism-related characteristics.
One such gene is called the DDX53.
While ongoing research aims to deepen our understanding of these genetic factors, scientists have found that there is a direct link between DDX53 and autism spectrum disorder.
Suspect 3: Other genes associated with autistic traits
Research into autism genetic factors has also uncovered key genes associated with autistic traits. One of these is SHANK3. Variations in the SHANK3 gene have been linked to brain development and autism spectrum disorder.
Other genes, such as CNTNAP2 and CHD8, have also been connected to an increased genetic risk of autism.
Suspect 4: Dad
Some scientists propose that fathers may carry protective genetic variations that sometimes fail to pass on to their children. Others hypothesise that paternal genetic material may interact with the mother’s immune system, potentially affecting foetal brain development.
It’s important to keep in mind that theories highlight the complexity of autism genetic factors and why we need further autism research to know what’s what for sure!
Generally, older fathers have a higher probability of genetic mutations, which may result in autism.
Fathers over 50 years old are 66% more likely to have an affected child than fathers under age 30. This is mainly due to the higher incidence of spontaneous mutation in the sperm as men grow older.
Suspect 5: Mum and her genetic and environmental factors
Well, research into maternal inheritance suggests that certain genetic variants may be inherited from mothers but remain silent due to protective factors in females, only manifesting when passed to male offspring.
But we also know that prenatal exposures such as maternal infections, stress, and certain medications can result in autism. Other studies have also concluded that maternal health conditions, including diabetes and hypertension, have led to an increased risk of autism spectrum disorder.
So, it’s not just mum and her genetic factors, but also her environmental factors that can impact her child.
Suspect 6: Environmental factors
While environmental factors do not directly cause autism, they are known to influence it when combined with genetic predispositions. These could include toxic exposure through air pollution or heavy metals, which could interact with genetic factors to impact brain development.
So, best to check what you eat and what you inhale. One study found that children exposed to high levels of PM2.5 during pregnancy had a 64% increased risk of developing autism spectrum disorder compared to those with lower exposure levels.
Another study found children exposed to the highest levels of NO had a 1.8 times greater likelihood of developing autism than those with the lowest exposure levels.
Other pollutants like benzene and NO₂ were also found to be responsible. These toxins have been associated with a 20–30% increase in ASD risk, likely due to mechanisms such as prolonged neuroinflammation.
Suspect 7: Birth complication
Some studies also believe that birth complications – like oxygen deprivation – could impact brain development, which, of course, is another layer of complexity that leaves scientists scratching their heads.
The jury is still out
For now, autism researchers continue to investigate the involvement of each of these suspects and the complicated genetic elements responsible for autism.
The great news is that with increasing advancements in genetic testing, scientists are slowly uncovering how genetic material is passed down and which genetic risk factors might contribute to an autism diagnosis.
This brings us to the next step: genetic testing.
Why early detection matters
Understanding how autism runs in families has the potential to be a game-changer when it comes to early diagnosis and support.
Fortunately for us, researchers are on a mission to crack the genetic code behind autism, which could in turn lead to better diagnostic tools – and maybe even personalised treatment plans.
This research will help families get a clearer picture of what to expect, especially when it comes to genetic counselling and planning for the future.
For years, people had blamed parenting styles (because, I guess it was easy), but newer studies confirm that genetics play a huge role.
So, if you were given the side-eye about your kid’s screen time habits, and wondered if it was really something you did – breathe easy. Science and research suggest otherwise.
Let's take a peek into the DNA playbook
Genetic testing for autism spectrum disorder (ASD) is like running a background check on your DNA -except instead of criminal records, scientists check for genetic abnormalities that might contribute to ASD.
In Australia, this process usually involves two main tests. The first is the Chromosomal Microarray Analysis (CMA) which scans for duplications or deletions in genetic material that could be linked to ASD. Think of this as a high-tech search for missing puzzle pieces in your DNA.
The second test is called the Fragile X Syndrome Testing. This test hones in on Fragile X syndrome, a genetic disorder connected to intellectual disability and ASD. If CMA can’t detect it, Fragile X testing steps in like the smart, experienced detective who always finds the missing clue.
Science is getting better at connecting the dots, but DNA is a tricky little code. So, while these tests can offer insights, they don’t hold all the answers – just a few more pieces to the ever-evolving autism puzzle.
FAQs about autism and genetics
Q. Should parents consider genetic testing for autism?
Genetic testing has its pros and cons.
On the bright side, it can give parents a behind-the-scenes look at if and how autism runs in the family. It also flags potential health risks beyond autism, such as the PTEN variant, which increases cancer risk, allowing for earlier preventive care.
This information is wonderful because it aids in better medical planning, early intervention, and finding suitable therapies. Plus, scientists also benefit from this research, because they can use your genetic data to refine interventions and inch closer to potential breakthroughs!
However, genetic testing isn’t a magic answer. It doesn’t diagnose autism outright; it simply highlights possible risk factors.
And while some folks believe there are privacy concerns, such as genetic discrimination affecting jobs, insurance, and even personal data protection, others also argue that this testing prevents ASD from being seen as neurodiversity.
However, many parents believe it is better to be in the know and favour genetic testing for the chance at earlier support and smarter healthcare planning.
Q: If I carry a mutation but don’t have autism, can I still pass it to my child?
Yes, genes are tricky like that. You might be carrying a genetic mutation linked to autism without showing any signs yourself.
But just because you have the mutation doesn’t mean your child will develop autism; it just increases the possibility. Sometimes, these genetic variations stay silent for a generation and then decide to make a grand entrance in the next. These are called inherited mutations.
Q. Can two autistic parents have a neurotypical child?
Yes, two autistic parents can have a neurotypical child.
While autism is strongly linked to genetic factors, the inheritance pattern is complex. Research suggests that if both parents carry different genetic variations associated with autism spectrum disorder (ASD), there may be a higher chance of their child being neurotypical.
Q. What are the main causes of autism?
Ah, the age-old question – right up there with “Why do toddlers insist on eating crayons?” To recap, while science doesn’t have all the answers (yet!), here’s what we do know:
One, autism has a strong genetic foundation, with a mix of inherited and spontaneous (de novo) mutations making each case unique – like a custom-coded operating system for the brain!
Some autistic kids inherit rare genetic mutations, while others develop them spontaneously, because, well, DNA likes to keep things interesting.
Other factors like maternal infections and exposure to harmful substances during pregnancy, advanced parental age, low birth weight, and preterm birth can also slightly increase the risk.
Q. Should I have another baby if my child has autism?
Deciding to expand your family when you already have a child with Autism Spectrum Disorder (ASD) is a deeply personal and emotional journey.
It’s natural to try and understand the odds before you take a leap of faith. Here’s what we know so far:
- Having one child with autism spectrum disorder does increase the likelihood of subsequent children being diagnosed with the condition.
- Siblings of autistic children have a higher prevalence of ASD compared to the general population.
But here’s the good news:
One study found that mothers who plan their next pregnancy 2.5 to 3 years after the birth of a child with autism spectrum disorder may lower the likelihood of having another autistic child.
Why? Scientists are still figuring that out, but it could have something to do with genetic and environmental factors during pregnancy. In short, your body might appreciate a little breather before diving back into baby-making mode.
Q. Could genetic testing help?
Yes and no. While genetic testing can offer clues, it’s not a crystal ball. (Not that those are accurate but you get my point!) It can’t tell you with certainty if your next child will be autistic or on the spectrum. That’s why chatting with a genetic counsellor or healthcare provider is a good move.
Remember, the decision to have another child is profoundly personal and should always take your and your partner’s feelings into account.
Our advice: Whatever you decide, just be sure to surround yourself with supportive communities and professionals who can help you navigate this journey with compassion and understanding.
Not many people realise this, but support groups are an invaluable resource for autistic people, parents, caregivers, and even other family members. They can provide a friendly, non-judgmental and open space to share your feelings, challenges and even the big, and not-so-big wins!
Q. My doctor says it’s sporadic autism. What does he mean?
Sporadic autism refers to cases of autism spectrum disorder (ASD) that occur randomly or without a known family history of the condition.
Unlike inherited or familial autism, which is linked to genetic factors passed down through generations, sporadic autism is thought to result from de novo (new) genetic mutations or environmental influences during pregnancy or early development.
Q: Are Asperger’s syndrome and autism separate conditions?
Not anymore! Health professionals once believed that Asperger’s syndrome and autism were distinct conditions, but research has since shown that they both fall under the broader diagnosis of autism spectrum disorder (ASD).
So instead of being separate categories, they’re now understood as different points on the same spectrum.
Q. What is the genetic testing process in Australia?
If a child shows signs of ASD, the process of genetic testing for autism in Australia requires an initial visit to a general practitioner (GP). The GP may conduct an initial assessment and refer the child to a developmental paediatrician or clinical geneticist for further evaluation.
Once testing is recommended, a DNA sample – usually blood and sometimes saliva – is collected for analysis.
This sample is then examined in a laboratory to detect any genetic abnormalities that may be linked to autism.
Once the results are ready, healthcare professionals meet with the family to explain the findings and discuss their implications. The entire process can take several weeks, depending on the specific tests ordered and lab processing times.
Avoid the blame game
Parenting is already filled with enough challenges – self-doubt, exhaustion, and the constant pressure to do what’s best for your child. When it comes to autism, playing the blame game only adds unnecessary guilt and stress to an already emotional journey.
For years, outdated theories have blamed mums for autism, from the harmful “refrigerator mother” theory to modern guilt around diet, vaccines, and parenting styles.
But scientists have since proved that autism is primarily genetic and neurological, not caused by parental actions.
Yet, parents still find themselves questioning: Was it something I did? Was it something I ate?
Blaming one parent over the other – whether it’s focusing on maternal genetic links or paternal age -creates division instead of support. The truth is, autism isn’t anyone’s ‘fault.’
Instead of dwelling on why a child is autistic, the focus should be on understanding their needs, advocating for the right support, and celebrating the unique strengths they bring into the world.
Parenting is a team effort, and families thrive on unity, not guilt. Whether it’s navigating therapies, education, or daily routines, parents and caregivers need to work together, uplift each other, and remember: autism is about love, acceptance, and embracing the child you have.
Once we have a clearer understanding of which parent’s genetics may contribute more to autism, the focus should not be on blame but on proactive steps that support the child and the family. While some things are beyond our control, here are some things we can control:
1. Genetic counselling and family planning
If autism is identified in a family, genetic counselling can help parents understand the likelihood of autism spectrum disorder in future children. While no test can predict autism with certainty, genetic screening can provide insights into inherited risk factors.
2. Early intervention and personalised support
In Australia, we’ve got some great organisations working hard to support autistic children.
Get in touch to learn about early intervention and find the support you need. Early detection allows families to access resources like speech therapy, occupational therapy, and behavioural interventions that can greatly improve outcomes.
3. Better understanding and acceptance
For autistic individuals, knowing their genetic history can provide a sense of self-understanding. It can also help parents, teachers, and caregivers approach autism with greater awareness, shifting the conversation from “Why?” to “How do we support them best?“
Wrapping it up
As our understanding of autism spectrum disorder continues to evolve, so does our knowledge of how genetic and environmental influences contribute to the condition. While environmental factors play a role, studies strongly suggest that genetic factors play a more significant role in developing autism.
Research suggests that autism is more frequently inherited from the father due to the presence of de novo mutations and the role of paternal age in passing on genetic variants. Nonetheless, both parents provide genetic material, and either may carry uncommon mutations that raise a child’s risk of developing autism spectrum disorder.
But ultimately, knowing who passed down certain genes matters less than knowing how to create an environment where autistic individuals can thrive.
The goal isn’t to empower families with knowledge, compassion, and the right tools to support their loved ones.
Support resources in Australia
In Australia, several organisations offer support and guidance for families navigating these decisions:
Sometimes Google just doesn’t cut it. That’s why these organisations exist:
- Reframing Autism – www.reframingautism.org.au
- NeuroClastic – https://neuroclastic.com
- Autistic Self Advocacy Network (ASAN) – https://autisticadvocacy.org
- Autism Level UP! – https://autismlevelup.com
- The I CAN Network (Australia) – https://icannetwork.online
- Yellow Lady Bugs – https://www.yellowladybugs.com.au/
Sources
Bai, D., Marrus, N., Yip, B. H. K., Reichenberg, A., Constantino, J. N., & Sandin, S. (2020). Inherited Risk for Autism Through Maternal and Paternal Lineage. Biological psychiatry, 88(6), 480–487.
Yoon, S., Munoz, A., Yamrom, B., Lee, Y. H., Andrews, P., Marks, S., Wang, Z., Reeves, C., Winterkorn, L., Krieger, A. M., Buja, A., Pradhan, K., Ronemus, M., Baldwin, K. K., Levy, D., Wigler, M., & Iossifov, I. (2021). Rates of contributory de novo mutation in high and low-risk autism families. Communications biology, 4(1), 1026.
National Institute of Environmental Health Sciences, Autism, February 2025
Queensland Brain Institute, What causes ASD, n.d
Related Articles
Loved this article?
Share with a friend
