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What Causes Autism? (Evidence-Based Causes of Autism)

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Table of Contents

Deciphering the enigma of what causes autism can often feel like a never ending journey. This complex blend of genetic and environmental factors continues to baffle even seasoned researchers. So as parents and health professionals, we can only talk about what they know so far.

Our blog will act as your compass, highlighting potential risk factors, debunking persistent myths and providing insights into current research into what causes autism spectrum disorders (ASD).

Key Takeaways

  • Autism Spectrum Disorder is not caused by one known cause.
  • Autism is caused by a combination of genetic factors, advanced parental age, certain pregnancy and birth complications, as well as environmental factors.
  • Older parents have a higher chance of having children with autism, but their age alone does not guarantee it.
  • Factors during pregnancy such as health problems and birth complications can be risk factors of autism in children.
  • Environmental factors like pollution, toxic substances, and infections during pregnancy may contribute to an increased risk of having a child with autism.
  • Autism is not caused by diet, vaccines, or bad parenting. There is no specific diet that can cure or treat autism spectrum disorders. Vaccines are safe and do not cause autism. Bad parenting does not cause autism either; it is influenced by genetic and environmental factors.

What causes autism spectrum disorder?

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Autism Spectrum Disorder (ASD) is not caused by one known cause (Raising Kids Network, 2021). It is believed to be caused by a combination of genetic factors and environmental factors, including, advanced parental age and certain pregnancy and birth complications (NIEHS, 2023).

Genetic component

There still needs to be more research done, however, initial research suggests that there are genetic factors that more likely increases the risk factors for autism spectrum disorder.

According to the Centres for Disease Control and Prevention (CDC, 2022), some additional risk factors are if the child has a sibling with autism spectrum disorder or have certain genetic or chromosomal conditions, like fragile X syndrome or tuberous sclerosis.

Older parents

Older moms and dads might have a higher chance of having kids with autism. Older parents being over age 45 (Autism Awareness Australia, n.d.). But it doesn’t mean for sure that they will have a child with autism. Older mothers also have an increased risk for pregnancy and birth complications (Autism Awareness Australia, n.d.).

The genes from both parents play a role. Still, older moms and dads should not worry too much about their age alone causing autism, as not one single factor can cause autism spectrum disorder.

Pregnancy and birth

Having a baby is a joy, but there are risks too. Things that happen when a mom is pregnant can play a part in autism. If mom has health problems during her pregnancy, like gestational diabetes or high blood pressure, it might raise the risk of autism for her child.

There’s also research that shows some link between birth complications and autism. For example, lack of oxygen during birth, a premature birth, children born with low birth weight or poor growth in the womb (Raising Children Network, 2021).

Environmental factors

Certain environmental factors can play a role in the development of autism. These factors include things like pollution, toxic substances, and certain infections during pregnancy.

What does not cause autism spectrum disorder?

kids playing sunlit day

Autism spectrum disorder is not caused by diet, vaccines, or bad parenting.


Vaccines are a topic that often comes up when we talk about what causes autism. But it’s important to know that there is overwhelming evidence that vaccines are safe and effective.

Two studies claiming that the MMR vaccine causes autism have been found to be flawed, and a court has even ruled against the theory. Vaccines do not cause autism. It’s crucial for parents to understand this so they can make informed decisions about their children’s health and vaccinations.


Maintaining a healthy diet is important for all children, including those with autism. However, it’s important to note that there is no specific diet that has been proven to cure or treat autism spectrum disorders.

While nutritional and dietary interventions are gaining popularity, it’s crucial to consult with healthcare professionals before making any changes to your child’s diet.

It can be challenging for individuals with autism to maintain a nutritious diet due to food sensitivities and gastroenterological issues they may face. Some individuals have reported positive effects on their child’s autism symptoms through dietary interventions, but more research is needed in this area.

Bad parenting

Some people believe that bad parenting can cause autism in children. However, this is not true. There is no scientific evidence to support the idea that parents are responsible for causing their child’s autism.

Autism is a complex neurodevelopmental disorder that is influenced by genetic and environmental factors, not by how a parent raises their child. It’s important for parents to know that they are not to blame for their child’s autism and should focus on providing love, support, and appropriate interventions to help their child thrive.


In conclusion, the cause of autism is a combination of genetic and environmental factors. It is not caused by diet, vaccines, or bad parenting. Understanding the risk factors and symptoms can help parents navigate their journey with an autistic child.

If you are concerned about your child’s development and potentially thinking about an autism diagnosis, please talk to your child’s doctor about this. An early diagnosis can help with providing early autism treatment that the child needs.

Check out our other ReadyKids blogs to learn more about autism spectrum disorder and how health professionals like occupational therapists, speech therapist, and psychologists can help.


1. What causes autism spectrum disorder (ASD)?

Autism is caused by a mix of factors such as genetic and environmental factors. Increased risk factors like having older parents, pregnancy and birth complications and siblings with autism, can increase the likelihood for a child to have autism spectrum disorder.

2. How does ASD affect a child’s development?

Autism Spectrum Disorder can affect each person in different ways. Some may have trouble with social interactions and emotional regulation. While others may have trouble with flexible thinking or challenging behaviours.

3. Can ASD be diagnosed early in a child’s life?

Yes, an autism diagnosis can be made based on the child’s communication and behavior before age 2. They may have issues with expressive language, repetitive behaviours or other signs that show up in early childhood.

4. Does having family history increase a child’s risk for autism?

Yes, having a sibling with Autism Spectrum Disorder increases the chance of your child having autism.

5. Are viral infections during pregnancy linked to greater risk for developing ASD?

Some scientific studies suggest that prenatal exposure to certain bacterial and viral infections might impact brain development leading to developmental disorders like Autism spectrum disorder (Queensland Brain Institute, n.d.)

6. Do childhood vaccines cause autism?

No! Extensive research has shown no link between childhood vaccinations and increased risk for developing Autism Spectrum Disorder (ASD).


Autism Awareness Australia (n.d.) Causes of Autism.

National Institute of Environmental Health Sciences NIEHS (2023). Autism.

Centres for Disease Control and Prevention (2022). What is Autism Spectrum Disorder?.

Queensland Brain Institute. (n.d.) What causes autism?

Raising Children Network (2021). Causes of autism.

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