Autism May Have Come From Ancestors, Scientists Say

Where and when your father's grandparents lived may increase your risk of autism, researchers find. Monkey Business Images/Shutterstock

Scientists from the University of Utah recently concluded that one’s ancestors—particularly where and when one’s grandparents and their children were born—may contribute to an increased risk of autism.

Recently published in the International Journal of Health Geographics, the study reveals that ancestors’ genetics carry a significant risk of autism spectrum disorder (ASD)—with the strongest signal identified from the birth and childhood of paternal grandparents.

Paternal grandparents’ nutrition in childhood, for instance, directly impacts health outcomes in grandchildren.

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“Looking back at families and where and when they lived helped us detect clusters of individuals who seem to have a higher subsequent risk of autism among their descendants,” senior author and environmental epidemiologist James VanDerslice from the University of Utah said.

The researchers identified information from 7,900 parents and 31,600 grandparents of autistic children born between 1989 and 2014 based on geographic and population data of families in Utah.

Study lead Rebecca Richards-Steed said what they found fitted in with the current scientific understanding of paternal genetics being key to evolutionary change and adaptation.

“So, it is quite possible in the case of autism that a signal, shaped in part by environmental experiences, is coming from the paternal lineage, which is being passed down through the family,” Richards-Steed, who is also a geography graduate at the University of Utah, said.

In contrast, their findings in rural areas showed a different pattern. Out of the 20 key clusters of autism, the researchers identified seven clusters from the rural regions that had a low risk of passing autism down the family tree.

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“We’re really not sure why some rural areas seemed to have what might be called a protective effect,” Richards-Steed said.

“It’s certainly possible that parents and grandparents living in urban areas had different environmental exposures or experiences.”

“What we can say, based on our findings, is what we are being exposed to now is probably not just affecting us or even our children but maybe even our children’s children.”

Incomplete Picture

However, the dramatic uptick in autism in the past six decades still leaves many unanswered questions.

The autism rate was one in 10,000 in the 1960s. By 2021, this had risen to one in 44 eight-year-olds on average. In California, where incidence is the highest, one in 28 eight-year-olds has a diagnosis of autism.

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According to the U.S. Centers for Disease Control and Prevention, this sharp rise is in part due to more comprehensive identification and diagnosis.

Physician Dr. Joseph Mercola said that mere diagnostic improvements cannot explain the significant upward trend.

Autism rates have reached new heights, with boys being over four times more likely than girls to be diagnosed. Dubova/Shutterstock

“One in 44 children were not autistic in the 1980s, with or without a diagnosis. Something is going on. One or more environmental factors are clearly having a devastating impact on our children,” Mercola wrote.

“Top suspects include childhood vaccines, toxic chemicals (glyphosate in particular), autoimmune antibodies, gut inflammation, retroviruses, and electromagnetic field exposure.”

“There’s no single answer to this problem. Since many different toxins can contribute, preventing autism must include the elimination of most toxic exposures.”