Risk of Autism Associated With When and Where Forebears Lived

Summary: Where and when grandparents and parents of children were born could contribute to an increased risk of ASD in their offspring.

Source: University of Utah

When and where are often vital clues for epidemiologists, the medical detectives who help solve the underlying mysteries of disease. The technique dates back to at least 19th century London, where a physician named John Snow mapped cholera deaths and traced the source of the outbreak to a single well in the city. Once the well was closed, the epidemic ended.

Taking this idea to a new level, University of Utah Health scientists, using a unique combination of geographic and population data, recently concluded that when and where parents and grandparents of Utah children were born and raised could contribute to an increased risk of autism among their offspring.

The scientists think this new approach could be used to explore time and space aspects of any disease where family pedigree information is available.

The study, published in the International Journal of Health Geographics, is among the first to assess the influence of time and space (when and where) across generations on the increased risk of autism.

In time, the researchers say, this finding could lead to the identification of environmental factors, such as exposure to pollutants, that could have disruptive effects on genetic information passed between generations.

“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,” says James VanDerslice, an environmental epidemiologist in the Division of Public Health at U of U Health and senior author of the study.

“Knowing that the parents and grandparents of these children with autism shared space and time brings us closer to understanding the environmental factors that might have influenced this health outcome.”

Epidemiological studies across generations are difficult and time-consuming, says Rebecca Richards-Steed, the study’s principal investigator and graduate student in the Department of Geography at University of Utah. In fact, most of these studies have been done in animals, which reproduce quickly and can be followed for several generations in a shorter time span than humans.

Using existing technology in a new way, VanDerslice and Richards-Steed circumvented this drawback by looking at existing data available for parents and grandparents to identify places and time periods that may be associated with risk factors that increased the risk of disease in subsequent generations.

The researchers used the Utah Registry of Autism and Developmental Disabilities, in conjunction with the Utah Population Database (UPDB), to identify parents and grandparents of children born between 1989 and 2014 who have autism.

Birth certificates, driver’s license information, and census and medical records in the UPDB helped the scientists track when and where these individuals lived over time. The UPDB is one of the few databases worldwide to include this type of information.

For comparison, they randomly selected parents and grandparents of children in the UPDB database who were not diagnosed with autism. Names of the individuals were withheld from the researchers.

In all, VanDerslice and colleagues pinpointed where 7,900 parents and 31,600 grandparents were born and raised. They identified 20 key clusters, or groupings, scattered across the state. After analysis, 13 of the 20 clusters—nine among grandparents and four among parents—were associated with an elevated risk of autism in their children or grandchildren. In particular, descendants of paternal grandparents were about three times more likely to have autism than expected.

“What we were seeing fits in with current scientific understanding of how paternal genetics is key to evolutionary change and adaptation,” Richards-Steed says. “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.”

Seven clusters, all in rural areas, had a low risk of an association between autism and family lineage.

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

This shows building blocks
The scientists think this new approach could be used to explore time and space aspects of any disease where family pedigree information is available. Image is in the public domain

Moving forward, the researchers will delve deeper into the factors, including lifestyle, that could help explain these results.

“Evidence shows our environment has a deterministic effect on our growth and development, which includes the germline cells we carry for the next generation,” VanDerslice says.

“Examining the shared space and time of our ancestors may give us clues about the environmental factors that may lead to biological changes that increase the risk of disease in future generations. “

The scientists think this new approach could be used to explore time and space aspects of other conditions where family pedigree information is available.

“This idea isn’t limited to autism,” Richards-Steed says. “It can be applied to any disease and could enhance our ability to understand how a confluence of genetic and environmental factors can have long-term health consequences for families.”

About this autism research news

Author: Press Office
Source: University of Utah
Contact: Press Office – University of Utah
Image: The image is in the public domain

Original Research: Open access.
Evidence of transgenerational effects on autism spectrum disorder using multigenerational space-time cluster detection” by Rebecca Richards Steed et al. International Journal of Health Geographics


Evidence of transgenerational effects on autism spectrum disorder using multigenerational space-time cluster detection


Transgenerational epigenetic risks associated with complex health outcomes, such as autism spectrum disorder (ASD), have attracted increasing attention. Transgenerational environmental risk exposures with potential for epigenetic effects can be effectively identified using space-time clustering. Specifically applied to ancestors of individuals with disease outcomes, space-time clustering characterized for vulnerable developmental stages of growth can provide a measure of relative risk for disease outcomes in descendants.


(1) Identify space-time clusters of ancestors with a descendent with a clinical ASD diagnosis and matched controls. (2) Identify developmental windows of ancestors with the highest relative risk for ASD in descendants. (3) Identify how the relative risk may vary through the maternal or paternal line.


Family pedigrees linked to residential locations of ASD cases in Utah have been used to identify space-time clusters of ancestors. Control family pedigrees of none-cases based on age and sex have been matched to cases 2:1. The data have been categorized by maternal or paternal lineage at birth, childhood, and adolescence. A total of 3957 children, both parents, and maternal and paternal grandparents were identified. Bernoulli space-time binomial relative risk (RR) scan statistic was used to identify clusters. Monte Carlo simulation was used for statistical significance testing.


Twenty statistically significant clusters were identified. Thirteen increased RR (> 1.0) space-time clusters were identified from the maternal and paternal lines at a p-value < 0.05. The paternal grandparents carry the greatest RR (2.86–2.96) during birth and childhood in the 1950’s–1960, which represent the smallest size clusters, and occur in urban areas. Additionally, seven statistically significant clusters with RR < 1 were relatively large in area, covering more rural areas of the state.


This study has identified statistically significant space-time clusters during critical developmental windows that are associated with ASD risk in descendants. The geographic space and time clusters family pedigrees with over 3 + generations, which we refer to as a person’s geographic legacy, is a powerful tool for studying transgenerational effects that may be epigenetic in nature. Our novel use of space-time clustering can be applied to any disease where family pedigree data is available.

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  1. This is absolutely ridiculous. Autism is genetic, it’s been around forever. The idea that it is this new thing caused by environmental factors (or vaccines) is laughable. Autism is not a disease to be cured, it’s a difference in learning and communication styles. Some cases are more extreme than others but it is all part of natural variations of the human brain. Life isn’t fair, it just does what it does.

    If you think we’d have even HALF the technological advancements we have today without autistic people, think again. They are thinkers, creators, engineers, scientists, physicists, etc. They’re the ones who truly understand systems.

    I always find it terrifying that some parents will perform all sorts of horrific things on their kids trying to cure their “autism”. My friend, if you have an autistic child, you and your partner are most likely on the spectrum as well, your friends closest friends are probably on the spectrum. Because these are the people who speak the same language as you. Open your god damned eyes.

  2. Women and girls mask autism symptoms, so I’m not sure that this will work except for the most severe cases of Autism Spectrum Disorder. Not to mention areas without as many pre-k services for younger children where Autism is noticed. Stick to your rats. At least there won’t be data you could accidentally ignore.

    1. I did a study myself and found states with high lead in water had higher cases of confirmed autism. That may explain why real living grandparents may have less exposure because they would probably have had well water

  3. “Unmitigated Horse Poop”, is the category to file many of the studies determining the causes of autism.

    One of my great grand sons is autistic. He is now twenty years of age.
    At the time of his birth, vaccinations being administered were a multi-combination of vaccines and preservatives.

    Prior to this event, autism was, for the most part, mostly unknown.
    The condition was an unknown in China prior to their adopting the use of vaccines produced by U.S. drug companies.

    Investigations should be about “How Did The Drug Industry” dodge the bullet?

    It’s all about $$$$$$$!

    1. It has been disproven multiple times that vaccines cause autism. There are autistic people who were never vaccinated, and it existed before vaccines were even a thing.

      If you’d rather have a dead child than an autistic one, you shouldn’t have kids.

  4. Autism. is it simply that they are born into a rural environment that changes the way they feel. For thousands of years we lived in small communities and inherited the skills to live in that environment (an emotional state?). If they then move into a different environment i.e. urban does this have a psychological/emotional effect?

  5. Trying to ignore the ableist tone of the article.
    But it seems to me that the ancestors of autistic people were likely to be autistic to. In which case the environmental factors you are looking for are probably not disease vectors but social, especially when comparing urban vs rural locations.
    Maybe those “protective” rural locations were societies that were particularly intolerant of people who were different meaning that neurodivergent families were more likely to move away.

    1. This. I thought that immediately with the rural comment. How much more likely is it that they’re just not diagnosed? Same with the grandparents.
      The whole tone of this was cringey and ableist. Autism isn’t a disease. There are so many holes in the findings of this study.

    1. I mean they should probably just rewrite this whole article to be less ableist because it’s pretty poorly written.

  6. Ok,here’s food for thought. Our family has a habit of keeping extensive family tree records and stories, no cases of Autism have been found in my parents or grandparents generations, yet our one son was diagnosed. I was born in one area and grew up 2 hours south of there, my husband was born in a completely different area (2.5 hours east of where I was born) and grew up 3 hours northeast of where he was born. Our daughters were born yet 2.5 hours away from any other place where we had been born or grew up and then we moved, so they grew up 3 hours north of where they were born and our 1 daughter had a son who was also diagnosed on the spectrum. Her hubby was born and raised 7 hours away. So we now have a son and grandson, both on the spectrum. Both come from parents that were not born in the same areas, nor grew up in the same areas, and did not have signs of family autism before this, yet in generations back to back there are 2 cases of it, in an uncle and nephew. We love them with everything and wouldn’t change them for the world. I just find it curious how the parents can come from such spaced apart places and grow up in such spaced apart places and yet the uncle and nephew are both diagnosed, if it is environmental factors

    1. It’s not. This isn’t good research at all. There are far more indicators that autism is genetic, and when only diagnostic information is used, we are ignoring the fact that we didn’t have the tools to diagnose many folks in our grandparents times.

  7. It sounds a little bit as if you are calling autism a disease, see comment by Richard-Steeds

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