Your DNA is changing all the time. Here’s why

Summary

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Short Wave – "Your DNA is changing all the time. Here’s why"

Date: June 9, 2026
Hosts: Emily Kwong (NPR)
Guest: Roxanne Khamsi (Science journalist & author, Beyond Our Ever-Mutating Cells)
Duration: ~15 minutes

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Episode Overview

This Short Wave episode dives into the fascinating, constantly shifting world of our DNA. Host Emily Kwong and guest Roxanne Khamsi explore how genetic mutations are a perpetual part of human life, not rare anomalies. They clarify what drives these genetic changes, how new discoveries are reframing the meaning and impact of mutation, and why understanding our ever-mutating cells is central to grasping health, disease, and even longevity.

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Key Discussion Points & Insights

1. Mutations: Ordinary, Not Extraordinary

• Mutation Is Unceasing:

  • Each day, trillions of mutations occur within the cells of a single human body.
  • Our DNA is not identical across all our cells due to constant “wear and tear”—genes turn on/off, break, and are imperfectly repaired.
  • Quote:
    • "We are kind of a landscape of genetic diversity, each of us, just by nature of all the DNA changes, all those errors that pile up over the course of our lives." – Roxanne Khamsi (01:11)

• Modern Sequencing’s Revelations:

  • Advances in DNA sequencing now allow scientists to analyze genetic differences cell by cell.
  • Majority of mutations are harmless 'background noise', but a small proportion can have profound health implications (03:57 – 05:28).

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2. What Causes These Mutations?

• Environmental & Lifestyle Factors:

  • Sunlight exposure leads to skin cell mutations (e.g., skin cancer).
  • Quality sleep is linked to fewer cellular mutations.
  • Scientists can trace specific behaviors, such as tobacco use, by reading the "signature" of mutations in individual genomes.
  • Quote:
    • "We now have the ability to dissect our mutations so much that scientists can actually look at the signature of your mutations ... and actually tell you if you have been smoking tobacco or chewing tobacco." – Roxanne Khamsi (05:36)

• Random Chance in Early Development:

  • Some impactful mutations happen purely by chance during rapid embryonic cell division.
  • Example: A newborn girl developed a heart mutation not inherited from her parents, but arising randomly during early embryonic development, shifting science’s understanding of inherited vs. spontaneous disease.
  • Quote:
    • "It's important for people to be aware of this if they want to kind of understand what's going on with their health." – Roxanne Khamsi (07:47)

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3. When Mutations Are Life-Saving

• ‘Natural Gene Therapy’:

  • Rarely, mutations act as spontaneous corrections for disorders, sometimes reversing otherwise deadly genetic diseases.
  • Example: Two boys with ADA-SCID (a severe immune disorder) survived because they developed corrective mutations, and similar phenomena have been observed in muscular dystrophy patients.
  • Quote:
    • "What you have to understand is that this then points to new treatments. Some people have called it natural gene therapy." – Roxanne Khamsi (09:54)

• Immune System Relies on Mutation:

  • Mutations help immune cells create new antibodies, which is fundamental for effective vaccination and disease resistance.
  • Quote:
    • "Our immune systems benefit from the process of mutation—that's one area in the body where mutations are critical to our health instead of detrimental." – Roxanne Khamsi (10:44)

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4. Mutations, Reproduction, and Aging

• Sperm, Eggs, and Parent Age:

  • Contrary to common belief, research shows 80% of new mutations in embryos originate from sperm, not egg cells, and sperm of older men accumulate many more divisions—and thus more mutations.
  • Quote:
    • "Eighty percent [of mutations] are actually traced to the sperm, not the egg." – Roxanne Khamsi (11:44)
    • "The older a man is, the more chance that he has all those mutations." – Roxanne Khamsi (12:28)

• Efforts to Slow Mutation and Aging:

  • Good sleep slows the accumulation of mutant cells.
  • Some centenarians have beneficial variants of the SIRT6 gene, crucial for DNA repair.
  • Companies are developing anti-aging therapies to repair or minimize DNA mutations, but it’s a complex challenge.
  • Quote:
    • "If we slow down mutation in the body, can we be specific enough? ... You need [mutation] to truly survive." – Roxanne Khamsi (14:11)

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Notable Quotes & Memorable Moments

• "People hear the word mutation and they immediately think about something negative. But there’re also good things that can happen with mutation." – Roxanne Khamsi (02:02)

• "I love the idea of having DNA that is repaired. My concern is how specific can it be, because ... our immune cells require mutation in order to make new antibody shapes." – Roxanne Khamsi (14:08)

• "I literally came home, it changed." – Emily Kwong (15:29)

• "It's been a pleasure mutating with you throughout it." – Roxanne Khamsi (15:26)

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Important Timestamps

• 00:20 – 01:21: Introduction to DNA variability and mutation
• 03:57 – 05:28: Ordinary vs. meaningful mutations; cell turnover and health
• 05:28 – 07:47: Environmental/behavioral mutation triggers and signature tracing
• 07:47 – 10:03: Randomness in early development; spontaneous disease correction
• 10:03 – 11:12: 'Natural gene therapy' and immune system mutation benefits
• 11:12 – 12:50: Reproductive cells, parental age, and dominant mutation sources
• 13:05 – 14:53: Anti-aging, DNA repair, the balance between beneficial and harmful mutation
• 15:19 – 15:29: Episode wrap-up and memorable closing exchange

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Conclusion

This engaging, fast-paced episode reframes mutations as not just agents of disease or dramatic evolution, but as a routine, omnipresent force—sometimes risky, often benign, and occasionally even lifesaving. With advances in technology, scientists can now parse these changes as never before, offering new perspectives on disease, health, and our shared, ever-mutating humanity.

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Transcript

[Announcer]

this message comes from schwab with the new schwab teen investor account teens can gain hands on investing experience and build positive money habits it's an account co owned by you and your teen so you can monitor and engage with the account while your teen learns how to invest and manage money learn more at schwab dot com you're listening to short

[Emily Kwong]

wave from npr shortwavers i'm going to take us back to high school biology the genetics chapter you may have learned that the human body is made up of trillions of cells and inside those cells are dna molecules those strands that contain the genetic code that makes you you but here's something that may surprise you and you may not have learned in school that dna is not the same for every cell and that's because dna is constantly changing there's actually trillions

[Roxanne Comsey]

of mutations happening in your cells every

[Emily Kwong]

day this is roxanne comsey she's a science journalist and a contributing writer at

[Roxanne Comsey]

the atlantic we're just constantly in flux partly because there's just wear and tear like genes will get turned on and sometimes things will break and then enzymes will come in and try to fix it but they won't always do the best job fixing it so we are kind of a landscape of genetic diversity each of us just by nature of all the dna changes all those errors that pile up over the course of

[Emily Kwong]

our lives by the way scientists have known for decades that our genes mutate it's just that in the last decade dna sequencing has gotten so much more powerful and precise that scientists can now read the genetic code of individual cells

[Roxanne Comsey]

there's been this possibility to kind of do a census of the cells in a body and figure out which ones have which mutations that the other cells don't have so then here we are grasping this diversity this genetic diversity that exists inside us and it turns out

[Emily Kwong]

there is a lot of genetic diversity inside us so much so that roxane wrote an entire book about it called beyond our ever mutating cells and a new understanding of health people hear the

[Roxanne Comsey]

word mutation and they immediately think about something negative but there's also good things that can happen with mutation so today

[Emily Kwong]

on the show genetic mutations like you've never seen them before out of the trillions of mutations happening inside us every day yes trillions which ones matter what do scientists know about them and if our dna is always changing then who are we really i'm emily kwong you're listening to short wave the science podcast from npr

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[Emily Kwong]

so usually when we talk about genetic mutations it's because something extraordinary arises from it like the formation of an entire species eventually or an inherited disorder but in your book you say mutations are ordinary they're as common as salt they are happening all the time what kinds of mutations are happening all the time

[Roxanne Comsey]

so yeah i guess i could have called this book like everyday mutations i mean you and i are mutating as we're having this conversation people listening to this are mutating as they're listening it's something kind of ongoing it's kind of the background noise if you will of

[Emily Kwong]

our lives because the cells are copying and just making errors all the time

[Roxanne Comsey]

yeah there's cell turnover all the time like our skin cells you wouldn't believe how many skin cells we shed our blood is turning over and it has implications for our health even these smaller scale mutations because there's a lot of mutation happening and a lot of it doesn't matter in our cells but every once in a while there is something that happens and it's not gonna cause a new species it might be an evolutionary dead end cause we're not gonna pass it on to the next generation but for the vast majority of the mutations in our bodies what matters is where it falls in the genome and if it falls in a place that matters and that that cell reproduces or replicates itself that's when you get into a situation where you know a spontaneous event can have really profound impacts on

[Emily Kwong]

our health are there any specific environmental factors or behavioral factors that trigger certain kinds of mutations so we know that

[Roxanne Comsey]

things like sunlight obviously cause our skin cells to mutate that's what's linked to skin cancer for example okay if you have good quality sleep if you sleep well that is actually linked to fewer mutant cells but what i found really striking is that we now have the ability to dissect our mutations so much that scientists can actually look at the signature of your mutations so where they fall in the genome and actually tell you if you have been smoking tobacco or chewing tobacco like that's how refined a picture we're getting of how our behaviors affect our cells so in the past people might have said oh don't it gives you cancer now we're actually saying okay don't chew tobacco or don't smoke tobacco because these are the actual kinds of mutations you're gonna get that may then precipitate something down the road so yeah behaviors cause cancer and then sometimes it's just you know chance say

[Emily Kwong]

more about that chance well what i

[Roxanne Comsey]

think is really interesting is that when embryos are dividing cells so like you know we all start with as one cell for the first twenty four hours of our life and then we're two cells and by day five we're one hundred cells with this hollow center that's one of the most active places of cell division in the course of our lives is this embryonic development and i spoke with this family that thirteen years ago their youngest daughter was born and like immediately taken to the icu the neonatal icu and they were trying desperately to figure out what was going on with her and what they thought she had was this condition called long qt syndrome but then they kind of looked and her parents didn't have it which was strange because this was thought to be an inherited disorder and what they found is that indeed she did have those cells mutated in her heart and the thinking is that since she didn't have the mutation throughout her body it was in that early kind of really dynamic embryonic cell cell division that a mistake was introduced in her dna and then passed on to part of her body just by chance just by chance so it has shifted our perspective of certain inherited diseases to be not just inherited but also spontaneously occurring and i think it's important for people to be aware of this if they want to kind of understand what's going on with

[Emily Kwong]

their health let's talk about this more instead of assigning a value judgment to like good mutation bad mutation there's just like mutations and there's different pathways in chapter six you talk about autocorrections where the human body by chance is mutating and like fixing itself what is an

[Roxanne Comsey]

example of that back in the nineteen nineties there were these two boys that should have not survived a condition that they were born with so they were born with something called ada scid which is an inherited immune deficiency and one of the boys actually had a brother that had passed away from it before he was born but these kids were doing fine and the doctors in new york couldn't understand it then they decided to look at the dna of these boys more closely and what they found out is that in addition to having the inherited disorder so the mutation that would have caused their immune systems to malfunction they actually had second corrective mutations that were actually allowing their immune systems to function well and this isn't just a fluke so that was with one immunodeficiency but they found it in patients like i don't know if people are familiar with duchenne muscular dystrophy now this is a disorder that's kind of a progressive muscle disease it's tragic it's extremely tragic because people die so young they was a case that again in like the nineties where the there was a patient who just wasn't progressing as they thought that he would and it was very interesting because it was one side of his body was doing better than the other and then they did the kind of cellular analysis and they found that actually earlier in his development one of his cells had actually acquired spontaneously a corrective mutation that essentially fixed the muscular issues that would have happened and it's kind of interesting as as case examples but what you have to understand is that this then points to new treatments some people have called it natural

[Emily Kwong]

gene therapy oh yeah yeah yeah your book talks about natural gene therapy in the context of skin disorders muscular disorders and anemia these kinds of spontaneous corrective

[Roxanne Comsey]

mutations it's amazing right i mean i look at our bodies as just completely dynamic like we are not static in any way it's almost like we're constantly playing the lottery in our cells and sometimes we get lucky and i think what we can now do because we have the dna sequencing technology is we can learn from that luck and we can replicate it and in fact you and i our immune systems benefit from the process of mutation that's one area in the body where mutations are critical to our health instead of detrimental yeah

[Emily Kwong]

that's a good point i mean vaccines are really capitalizing off our ability to mutate right they wouldn't work if our cells couldn't do that yeah so you write in a different chapter called the next gener quote most of the time when doctors talk about the risk of genetic problems in parents reproductive cells they focus on egg cells and embryo of course comes from an egg cell and a sperm cell when they come together but scientists have started to look also at sperm cells and how their genetic mutations could shape the embryo what has research found there you know first of

[Roxanne Comsey]

all i want to back up and say i am a woman who had a child at age forty two and i got a lot of concern amongst the doctors about my age and it's true that chromosomal ab do increase so chromosomal abnormalities refer to like the big bundles of dna that happen in our cells and sometimes they don't sort so perfectly well if an egg is from a woman who's older the bulk of new mutations that occur in the reproductive cells that form our kids eighty percent are actually traced to the sperm not the egg eighty percent that is a

[Emily Kwong]

lot that's like four out of every

[Roxanne Comsey]

five mutations yeah and that's because in part sperm are not quite as good at defending against mutation as egg cells it seems from what scientists have kind of uncovered so i mean at the risk of sounding like the doctors who talk to me about my age and my fertility yes the sperm of a twenty five year old man is the result of around three hundred fifty cell divisions and in contrast the sperm of a forty five year old man traced back to more than seven hundred fifty cell divisions so it's almost it's like more than twice the number of cell divisions and every time there's a cell division there's opportunity again for those mistakes to happen yeah so the end story is the older a man is the more chance that he has all those mutations so i think it's more just shifting the focus not just from women and just kind of placing on everybody to say look everybody as they get older have more mutations in their reproductive

[Emily Kwong]

cells i mean given that the number of genetic mutations increases with age for everybody there is kind of an effort by some people to slow down mutations themselves like slow down the aging process how does that work well first of

[Roxanne Comsey]

all i want to mention again what i said earlier which is like sleep seems to like slow down the rise of some mutant cells in our body

[Emily Kwong]

so you're like i have a very futurist idea to propose to you all let's get enough sleep that could be a really good thing yeah but like

[Roxanne Comsey]

put that aside there are people who are looking at factors that contribute to longevity and how is mutation playing a role in that so interestingly centenarians so people who live one hundred years or more have been found to have certain variants of the sirt six gene which is involved in dna repair so there's companies now looking at all this data and actually trying to kind of explore the idea of slowing our mutation down

[Emily Kwong]

yeah i'm curious what you think because right you write about these companies in the uk and in the us that are looking at these anti aging therapies that look for and correct genetic mutations do you think that is a worthwhile enterprise for all i love the idea

[Roxanne Comsey]

of having dna that is repaired my concern is how specific can it be because as i was alluding to our immune cells require mutation in order to make new antibody shapes so every time we get sick you might be able to hear i'm coming over a cold so this happened in me recently i got some kind of bug from my kid who's in daycare and i'm sure because i know how the immune system works that my immune cells were essentially doing that lottery thing they were pulling that leverage reshuffling their dna inside them and coming up with new antibody shapes to fight this pathogen so my point going back to the aging question is that if we slow down mutation in the body can we be specific enough so we can slow down mutation where we don't want it but then keep it where we need it keep it in the immune cells that are doing dna changes in order to come up with antibodies that are new because that's what we need to truly survive we're now grasping that spontaneous mutations in the body are affecting our health and we're gonna just feel so much more empowered when we get a handle on this

[Emily Kwong]

roxanne this conversation may have changed how i see humans us this has been really fantastic well it's been a pleasure

[Roxanne Comsey]

mutating with you throughout it oh the

[Emily Kwong]

pleasure's mine i literally came home it changed this episode was produced by hannah chin it was edited by rebecca ramirez and fact checked by tyler jones jimmy keeley was the audio engineer i'm emily kwong thanks for listening to short wave the science podcast from npr

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[Emily Kwong]

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