How Autism Can Look Very Different, Even in Identical Twins

This episode explores the complexities of autism spectrum disorder, particularly how it can manifest differently between identical twins with the same genetic makeup.

1. Autism spectrum disorder can manifest differently even among genetically identical individuals.
2. Environmental factors and early life experiences, like illness or surgery, may influence the severity and characteristics of autism.
3. The study of identical twins provides critical insights into the genetic and environmental factors affecting autism.
4. Misconceptions about autism, such as the debunked "refrigerator mother" theory, have evolved significantly due to scientific research.
5. Understanding the nuances of autism in twins can help in developing targeted interventions to aid communication and social integration.

1: Introduction

John Hamilton introduces the topic and the twin brothers, Sam and John Fedders, highlighting their different experiences with autism.
John Hamilton: "They are at really different places on the autism spectrum."

2: Differences in Development

Discussion on how despite identical genetics, the twins exhibit varying developmental challenges and abilities.
Sam Fedders: "He knows, like, every single episode of Sesame Street. He has them all stored in here."

3: Scientific Insights

Exploration of the scientific studies and theories related to genetic and environmental impacts on autism.
John Hamilton: "Understanding the difference between identical twins like Sam and John will help show what changes in the brain result in autism."

4: Parental and Environmental Factors

Details on how early life conditions and parental experiences might influence autism's severity.
Kim Laird: "John was born with a congenital heart defect... he developed a really bad staph infection in his incision scar."

5: Conclusion

Reflections on what has been learned from twin studies and their implications for understanding autism.
John Hamilton: "Understanding that might be really useful in figuring out how to help someone like John acquire more language."

1. Learn about the genetic and environmental factors influencing autism to better support affected individuals.
2. Encourage inclusive environments that accommodate different communication styles and needs.
3. Support research and organizations dedicated to studying autism, especially nuanced cases like those of identical twins.
4. Educate others to dispel outdated myths and promote a better understanding of autism.
5. Foster patience and understanding in interactions with individuals on the autism spectrum.

Sam and John Fetters, 19, are identical twins on different ends of the autism spectrum. Sam is a sophomore at Amherst College and runs marathons in his free time. John attends a school for people with special needs and loves to watch Sesame Street in his free time. Identical twins like Sam and John pose an important question for scientists: How can a disorder that is known to be highly genetic look so different in siblings who share the same genome?

People

Sam Fedders, John Fedders, Kim Laird

Companies

None

Books

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Guest Name(s):

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Content Warnings:

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Regina Barber
You're listening to short wave from NPR.

Identical twins are identical, right? Well, not completely, and especially not when it comes to autism spectrum disorder. Here to chat about this is NPR's resident Brainophile, John Hamilton. Hey, John.

John Hamilton
Hey, Gina.

Regina Barber
Okay, so I understand you've been reporting on autistic twins as part of the NPR series on the science of siblings.

John Hamilton
I have, and I was lucky enough to spend some time with a pair of identical twin brothers who are at really different places on the autism spectrum. Their names are Sam and John Fedders. They are 19. They are very tall.

Sam is six five. John is six four.

Regina Barber
Wow.

John Hamilton
Here's how Sam describes John, who is sitting right beside him on the couch while we talk.

Sam Fedders
He's so smart.

He knows, like, you know, like every single episode of Sesame street. Yeah, and the Muppet show.

John Fedders
Yes.

Sam Fedders
He has them all stored in here in a way that is, frankly, extremely impressive to me.

John Hamilton
And here is what John says when I ask him to describe his brother.

John Fedders
He's Sam.

John Hamilton
He is definitely Sam. And what does Sam like to do?

John Fedders
He using his computer.

John Hamilton
What does he do on his computer?

John Fedders
Using his games.

Regina Barber
Theyre different for sure. But has that difference affected their lives?

John Hamilton
It has. Sam is a sophomore at Amherst College. John goes to a school for people with special needs.

Sam loves to talk. He can carry on a conversation about pretty much anything.

For John, autism has made language a real challenge. He also tends to repeat the words he's just heard, and he flaps his hands. Sam told me those behaviors make his brother really vulnerable when people are cruel.

Sam Fedders
Someone compared me to rain man once, and one of the ways you avoid that is trying to, like, present much more neurotypical.

And I can do that.

My brother cant.

Regina Barber
Ok, so they have the same genes, but a different result. Do scientists know why?

John Hamilton
Not yet, but theyve got some ideas. And the hope is that understanding the difference between identical twins like Sam and John will help show what changes in the brain result in autism.

Regina Barber
Today on the show, what scientists are learning from identical twins on the spectrum. Im Regina Barber. Youre listening to Shortwave, the Science podcast from NPR.

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Regina Barber
Okay, I know identical twins have exactly the same genes, but what does that mean for an autism diagnosis?

John Hamilton
Autism is this highly genetic condition that seems to involve multiple genes. It runs in families quite often. And in a given family, if one sibling is autistic, there's a much greater chance that the other siblings will be as well.

Where you really see the difference, though, is in identical twins, because, I mean.

Regina Barber
If something's genetic, you'd see it in both people, right?

John Hamilton
Not always is the answer there. You know, if one identical twin is on the spectrum, it is really, really likely the other twin will be as well. At least one study showed there was more than 90%, what they call concordance.

What's interesting is that these genetically identical siblings can have really different levels of autism, like Sam and John, the twins we heard from before the break.

Regina Barber
Does that mean that it's not just about genes, but there's, like, other factors involved in how autism manifests?

John Hamilton
That's what scientists think. They're still trying to understand which factors, though 1 may be that one twin experiences an injury or an illness that somehow makes their brain react differently to the genetic factors that are involved in autism.

Regina Barber
Could any of those things explain why Sam and John are different? Like, when it comes to autism?

John Hamilton
Maybe. I mean, there's no way to be sure, but this is something I talked about with their mom. Her name is Kim Laird.

Kim Laird
John was born with a congenital heart defect, and it turned out he needed heart surgery to close his, the hole in his heart, it was that big. So he got through that and he developed a really bad staph infection in his incision scar, and he had a central iv and really strong antibiotics.

Regina Barber
That's a pretty harrowing way to start. I mean, does their mom think that's what made John's autism so different than Sam's?

John Hamilton
Kim isn't sure, but she told me that the difference between Sam and John really wasn't that apparent. When her boys were toddlers, they were very similar.

Kim Laird
They both did not wave. They didn't respond to their name.

They both had a lot of repetitive, you know, movements. They would line things up and open and closed doors.

And it was only when Sam started talking and we were like, well, what's going on with John?

Regina Barber
So do scientists have any idea of how something like infection could make autism more severe?

John Hamilton
They have some hypotheses, right? Scientists always do. There's some thinking that maybe something like that could limit the brain's ability to adapt to genetic differences that influence things like language. That's speculation, of course. But what is clear is that identical twins offer this amazing window on the interaction between the DNA that you start out with and what happens to you early in life and how it affects brain development and where you fall on the autism spectrum.

Regina Barber
Yeah, I mean, what have scientists learned so far from studying twins?

John Hamilton
One thing they've learned is that the conventional wisdom about autism from 50 years ago was completely wrong.

Regina Barber
Wow.

John Hamilton
Okay, keep in mind that was a time when psychoanalysis was big and a lot of disorders were attributed to your experience as a young child. All went back to that, right? Yeah, I talked about that with doctor Stephanie Morris. She's a pediatric neurologist at the Kennedy Krieger Institute in Baltimore.

Stephanie Morris
The earliest, earliest twin studies really helped to debunk this theory that autism was caused by parenting, by these, what were referred to as refrigerator mothers. Right? Which is this concept that autism was a direct result of moms in particular, who were cold and emotionally detached and distant from their child.

Regina Barber
Like, I've never actually heard of refrigerator moms, but of course it must be the mom's fault, right?

John Hamilton
Yeah, tempting for a lot of those researchers, but no, that's not how it played out. The twin studies were really critical to showing that because they let scientists study kids the same age who'd been raised by the same parents. And guess what? Parenting doesn't make kids autistic. But when scientists began studying identical twins, they realized that genes aren't the complete explanation either. There's gotta be something else going on.

Regina Barber
So with Sam and John, it could have been this heart surgery or the infection or all those antibiotics. But what are the other things scientists are looking at?

John Hamilton
One thing is the condition in the womb, you know, the environment of the womb during pregnancy.

Regina Barber
That's what I was thinking.

John Hamilton
I mean. Cause twins aren't necessarily the same. One might get more odd or more nutrients than the other during pregnancy, then either before or after birth, maybe one twin is exposed to a toxin or something while the other isn't. And Stephanie says even though identical twins start out with identical genes, this doesn't mean all their cells turn out exactly the same way.

Stephanie Morris
There's also this concept of other non shared genetic factors that could be influenced. Things like epigenetics, which is the modification of our DNA that happens over time as a result of both gene gene interaction as well as gene environment interaction.

John Hamilton
So, as you can hear, scientists are still trying to figure out how all of these factors change brain development in autism. And it's tough, because when you compare the brain of an autistic person with the brain of a neurotypical person, the differences are really subtle, if they're detectable at all. So, for example, there seems to be a slightly different growth pattern in the brain with autism. And the connections between brain areas seem to be slightly different.

Regina Barber
So are twins going to be the best way to find these brain differences?

John Hamilton
That's one way. I think scientists would love to know precisely how Sam's brain and John's brain are different and when that difference occurred.

Understanding that might be really useful in figuring out how to help someone like John acquire more language. It might make it easier for him to communicate with his mom and his brother.

Regina Barber
I mean, how does John communicate now? Like, when he can't find, like, the.

John Hamilton
Right words, sometimes he points to a favorite episode of Sesame street. Other times he communicates physically.

When he and Sam are together, and I was with them quite a bit, John stayed really close to his brother, and he often wanted to be in physical contact.

He likes to have Sam hold his hand when they go places. Here's what Sam told me about this.

Sam Fedders
Touch is a way of, like, communicating, too.

If language isn't as much a method of communication, then all the other senses become a lot more kind of important and meaningful.

Regina Barber
Sam sounds like a great brother.

John Hamilton
He really is. And he is also really good at.

I don't know what to say. Translating for John.

For example, I was there when Sam kind of stepped in when I asked John to name his favorite episode of Sesame Street.

John Fedders
Abby makes the season change.

John Hamilton
Say that again.

John Fedders
Abigail makes the season change.

Sam Fedders
There's an episode with Abby, Kadabby, Rosita, and Zoe where they dance around with, like, the seasons changing. And I think that's the one he's referring to.

John Hamilton
And Sam told me that he does wish it was easier for his brother to express all the thoughts and feelings he's having. But he also said you know, that's kind of a small thing.

Sam Fedders
He still means the world to me, and I wouldn't have him any other way.

Regina Barber
Thanks, John. I'm really glad I got to know these brothers at least a little bit.

John Hamilton
Me too, Gina.

Regina Barber
This episode was produced by Rachel Carlson and edited by our showrunner Rebecca Ramirez. John, check the facts. The audio engineers were Phil Edfers and Gilly Moon. Beth Donovan is our senior director and Colin Campbell is our senior VP of podcasting strategy.

I'm Regina Barber. Thank you for listening to short wave from NPR.

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