‘Autism Is Genetic’, Says National Autistic Society

For the first time, a UK charity supporting autistic people has stated definitively that “autism is genetic”.

The National Autistic Society (NAS) said the declaration comes in response to “false claims about autism in the media and politics in the UK and the US, which are spreading harmful lies” and detracting from the issues autistic people face.

The charity’s research team looked at 83 studies on the causes of autism, and concluded from the findings that “autism is genetic” and “most autistic people are autistic because of genes they got from their parents”, which is why it often runs in families.

They added that it isn’t to say other factors don’t play a role, but these factors are “usually in combination with genes from parents”.

“There isn’t a single ‘autism gene’,” the charity added. “Thousands of genes combine to make a person autistic. Scientists have identified many of these genes, but they think there are still many more to find.”

NAS also warned that there is no genetic test for autism – and such testing can’t predict whether a child will be autistic or not, nor can it diagnose someone.

The update comes a year after the president of the United States, Donald Trump, claimed that taking paracetamol – or acetaminophen, as it’s known in the US – in pregnancy is linked to rising autism rates. A study from 2021 revealed there had been a 787% increase in autism diagnoses between 1998 and 2018.

At the time, Trump’s comments were condemned by medical experts, charities and Tylenol maker Kenvue, which told the BBC the science shows that taking acetaminophen does not cause autism and added: “We strongly disagree with any suggestion otherwise and are deeply concerned with the health risk this poses for expecting mothers.”

In August this year, Trump signed an executive order limiting the number of vaccines recommended for children, after linking them to autism. At the time, he said: “Decades ago, children received only a small fraction of the vaccines required today. In those times, people were much healthier and of course the high rates of autism now observed did not exist.”

Studies show that vaccines are not associated with autism.

A panel of 300 autistic people and their family members responded to the National Autistic Society’s review, with 64% believing the information that ‘autism is genetic’ would help dispel myths about the causes of the neurodevelopmental difference.

But many also expressed concern that it could lead to parental guilt or blame.

In response to the charity sharing its findings on Instagram, one follower shared: “Good to be informed. Also never felt more guilty knowing it’s my own fault.”

“This comes as no surprise to me,” added another commenter. “My father and grandfather were autistic, so am I and so is my son.”

Dr Rachel Moseley, Principal Academic in Psychology at Bournemouth University, told HuffPost UK that “while this information is not new to the scientific community, the National Autistic Society are to be credited for giving official recognition to an evidence base which has been inappropriately cast in doubt”.

Prof Rosa Hoekstra, Professor of Developmental Disabilities at the Institute of Psychiatry, Psychology and Neuroscience (IoPPN), noted it’s widely accepted in the autism scientific community that in high income countries, autism is strongly genetic. (She added there is less known about autism’s causes in low-income countries, where exposure to infectious diseases may play a role.)

“This statement is thus not new. But given the prominent misinformation about vaccines or paracetamol as a cause of autism, this clear statement from the NAS, which serves autistic families in the UK, is welcome,” added Prof Hoekstra.

Dr Mark Aszkenasy, consultant paediatrician at Care ADHD and author of The Genetics of Autism, told HuffPost UK he also agrees with the National Autistic Society’s central conclusion that autism has a strong genetic basis.

“Decades of twin and family research show that genetic differences explain most of the variation in people’s likelihood of being autistic. This is not a new discovery, but it is an important message to communicate clearly,” he said.

“That does not mean there is a single ‘autism gene’, or that other influences on early brain development are irrelevant. The biology is complex, and we should be clear about what we know without pretending we have every answer.”

Dr Claudia Aymerich, consultant psychiatrist at Berkeley Psychiatrists, also supports the charity’s conclusion. “The evidence for this has been building for decades through twin and family studies, alongside increasingly sophisticated genetic research,” she said. “However, I think it is important to be precise about what we mean when we say that autism is ‘genetic’.”

“Autism does not result from a single ‘autism gene’, and there is no simple genetic test that can currently tell us whether someone will be autistic,” Dr Aymerich explained.

“Its genetic architecture is highly complex, involving many different genetic variants, each of which can contribute differently to an individual’s likelihood of being autistic. Some genetic changes can also arise spontaneously rather than being inherited directly from a parent.”

That being said, while evidence strongly supports a genetic basis for autism, she’s cautious about presenting genetics as a simple explanation for every individual case.

“The research points towards a complex interaction between many genetic factors, rather than one straightforward cause,” she added.

The psychiatrist is also keen to stress that discussions about the genetics of autism “do not inadvertently reinforce the idea that autism is something that needs to be ‘fixed’ or prevented”.

“Autism is a neurodevelopmental difference, and understanding its biological basis should ultimately help us understand autistic people better and improve the support available to them, rather than simply searching for a cause or a cure,” she said.

Parents shouldn’t blame themselves or feel like they’ve done something wrong, either.

“Genetic influences are complex, and in many cases we cannot identify precisely why one individual is autistic,” the expert continued.

“Ultimately, the value of research like this is in improving our understanding of autism and challenging misconceptions about its origins.

“That understanding should be used to improve recognition, diagnosis and support for autistic people, while respecting the considerable diversity of their experiences, rather than reducing autism to a single cause or using genetics as a basis for seeking to prevent or ‘cure’ it.”

Dr Askenasy added that “autism is not caused by bad parenting or vaccines”.

“Families need accurate information, not blame,” he ended, suggesting the priority should be timely assessment, appropriate education and practical support that reflects each autistic person’s needs.