This blog post is an updated response to an Ask an autism researcher question from 2019.
Can I pass [autism] on to my children?
This is a very difficult question to answer, because there are different underlying genetics for autism with some being highly heritable and others not.
Autism is a neurodevelopmental difference that affects social communication and interaction, as well as engagement in non-social differences such as repetitive behaviours, intense interests, and/or unusual sensory experiences. While we have seen a rise in research exploring genetic links to autism, the reality is that a combination of genetic and environmental factors likely contributes to this difference.
The genetic expression of autism is complex, and research is still uncovering the specifics. This complexity is likely due to the heterogeneity of autism, with inheritable genetic factors and de novo gene variations (a change in the DNA sequence of a gene seen for the first time in a person and has not appeared in previous generations). So far, scientists have identified 300 to 400 genes that could be involved, but the exact combinations remain unclear.
Despite many studies focusing on the genetic underpinnings of autism, researchers have only been able to link genetic variations to a small portion of Autistic people. This challenge, often called the “missing heritability problem,” is seen in many complex genetic conditions. Researchers believe that many genes are involved, and the specific genetic variations may differ from one person to another.
There is evidence that autism tends to run in families. For example, 60-90% of identical twins share Autistic traits compared to only 5-40% of non-identical twins (Hu et al., 2019; Colvert et al., 2015). Even if parents or extended family members do not have an autism diagnosis, they might carry genetic variations associated with autism, which they can pass on to their children.
When there is one Autistic child in a family, the likelihood of having another Autistic child rises. Approximately 3-4% (3-4 in 100) of children in the general population are Autistic. This rate increases to nearly 20% (1 in 5) for families with one Autistic child.
Thank you to Dr Elfriede Ihsen who authored the original version in 2019.
