Autism and Twins

Greetings Earthlings! 🙂

This week I’d like to talk about a really interesting research area- autism and twins.

Oh my God two Aoife’s! 😲

Haha don’t worry there’s only one me- I don’t think the world is ready for me to have a clone!

But have you ever wondered what happens if an autist is a twin? Researchers have- they’ve been examining autism in pairs of twins for years and the results have a lot to tell us.

The evidence shows that in up to 90% of twins where one sibling is autistic, the second sibling is also on the spectrum. Identical twins share the exact same DNA (although fun fact, they have different fingerprints due to varying blood flow levels to each baby in the womb! 😀 ), so given that the root of autism is thought to be largely genetic, it makes sense that they would also be identical in this regard.

Interestingly, as no two cases of autism are the same, this holds true for identical twins. Severity can vary greatly among twins, so while both may be autistic, they may each have very different traits. Social trait severity in particular can vary between twins. In one study for example, one twin was nonverbal while the other had no speech issues. This demonstrates that while genetics may cause autism, they don’t always influence traits and severity, so just because your DNA says that you’re autistic, doesn’t mean that your quality of life is defined by your genome. That being said however, the reason for these differences has slightly baffled researchers as identical twins share the same DNA and environment, so the differences in severity is intriguing.

In the case of fraternal twins who do not share the same DNA, there is also a high chance that both twins will be autistic. It’s thought that this may happen as both twins share the same womb, they are exposed to the same in utero environmental factors such as stress, diet, drugs, maternal age etc.

The factors for autism development are many and varied, but twin studies certainly give us a lot of food for thought.