Confirmed: Heredity Is the Main Cause of Autism

Autism is defined as a neurodevelopmental disorder indicated by impaired social interaction, non-verbal and verbal communication, and repetitive or restricted behavior. Figures show that 1 in 68 children has been diagnosed with autism. The disorder is more prevalent among boys (1 in 42) than in girls (1 in 189), according to the CDC[1]. The exact cause of autism is still unknown, but scientists theorized multiple factors play a role. The latest study showed heredity is the main cause. We bring you all the details.

Genetics And Autism

The fact that the underlying cause of autism isn’t known, didn’t stop scientists from speculating about potential factors. For many years, studies have shown that a combination of environmental factors and genetics plays a role. But, Sven Sandin and a team of scientists at the Icahn School of Medicine at Mount Sinai, New York wanted to know more about this subject. They decided to carry out a study to determine whether autism runs in families and, thus, to confirm or debunk the claim that genetics could be the cause.

For the purpose of their research, scientists evaluated statistics from a previous cohort study that followed children born in Sweden between 1982 and 2006. The children were followed until 2009 in order to determine whether they would develop autism. The primary objective here was to find out how common autism is in different types of siblings.

A total of 37,570 pairs of twins were included in the study, as well as 888,000 pairs of half-siblings and 2.6 million pairs of siblings. Results of the research, published in the JAMA[2], revealed that about 14,500 kids developed autism. The race and ethnical background of the children weren’t revealed, but it is a well-known fact that kids of all races and nationalities can develop this neurodevelopmental disorder. The findings confirmed that genetics could be the primary cause of autism.

Are There Some Specific Genes That Lead To Autism?

Previous studies tried to identify different sets of genes that could be associated with autism, but this research was different. The study only proved that genes play a major role, but the scientists didn’t pinpoint to the specific gene that causes autism and it wasn’t even a part of their study.

Interestingly, when scientists tracked diagnoses of autism over time among sibling pairs, they discovered that heredity accounts for about 83% of the risk of developing the disorder. These results[3] only confirm the previous study of twins which found that genetics accounts for 90% risk of autism. Even more shocking is the fact that heredity of autism is higher than in some psychiatric conditions like schizophrenia or ADHD.

What Makes This Study Different?

The latest research is, probably, the best piece of evidence that genetics is vital in autism development. But, you have to wonder what sets it apart from other studies on the same topic. Well, one of the previous studies analyzed data focusing on siblings both of whom were diagnosed with autism.

This research focused[4] on siblings as well, but they made an important change. Unlike prior studies, they didn’t focus at one point in time when both siblings had autism. Instead, they considered the fact that not both siblings will develop disorder simultaneously. Children may start the study without autism, then develop it over the course of research period at different rates. This simple change allowed them to get more accurate results.


Even though the exact cause of autism is unknown, the latest study confirmed that heredity plays the vital role. In fact, about 83% of the autism risk accounts for genetics. This important discovery only calls for more research to uncover all the mysteries associated with autism.

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