The cells we share

Fetuses leave cells behind in their parents' bodies, where they braid themselves into tissues, and remain, for years. What are they doing in there? (Originally aired in 2023) Guests: ⁠Amy Boddy⁠, Associate Professor of Anthropology at the University of California, Santa Barbara; ⁠Lee Nelson⁠, Professor Emeritus at the Fred Hutch Cancer Center For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ And please email us! ⁠⁠⁠⁠⁠[email protected]⁠⁠⁠⁠⁠ We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ Thank you! Learn more about your ad choices. Visit podcastchoices.com/adchoices

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• 1:21Speaker 00

  Okay, so I'm recording. Do you want to just first start by, can you say your name and how you know me?

• 1:30Speaker 02

  My name is Anne Bird Platt, and I am Bird Pinkerton's mother.

• 1:36Speaker 00

  That's my mom. And I called my mom after I found out this fascinating thing. Basically, that some cells from my body are probably hanging out inside of her body and have likely been there for three decades, like ever since she carried me in her womb. And as I told her, those cells, cells that are genetically me, it seems like some of them might have stuck around in your body and become a part of you. And I am curious what you make of that.

• 2:13Speaker 02

  You can't have the back.

• 2:19Speaker 02

  You want to use a quote, use that quote. You can't have them back.

• 2:25Speaker 02

  You're mine.

• 2:26Speaker 00

  Thanks, Mama.

• 2:26Speaker 02

  Oh, mine.

• 2:29Speaker 00

  Great. Thank you for telling me how to do my job.

• 2:33Speaker 00

  So my plan here was to explain to my mom very briefly sort of what those cells could be doing inside her and what similar cells are doing to parents all over. And that plan went without a hitch. Um, can you, I mean, now, since you're helping me out, can you ask me, what are they doing inside my body? What are these cells doing inside my body?

• 2:55Speaker 02

  I, can I ask it as a statement?

• 2:57Speaker 00

  What do you mean, can you ask it as a statement?

• 3:00Speaker 02

  I hope these cells are behaving themselves, that, you know, they're playing nicely with my cells.

• 3:09Speaker 00

  Well.

• 3:10Speaker 02

  I, I mean.

• 3:11Speaker 00

  So here's the, the fun twist. Researchers don't know. It seems like, you know, maybe something like a parent-child relationship. Some of the things that these cells might be doing might be good. Some of them might be somewhat less good. Uh, some of them might be totally neutral and researchers just don't know.

• 3:39Speaker 02

  Define less good.

• 3:43Speaker 00

  All right. Well, let's get into it. Uh, do you want me to tell you a little bit about all, like, okay, so I'm gonna, I wasn't actually, I was just gonna walk you through that intro, but why don't I just tell you the whole episode and see what happens? Okay. Do you have something?

• 3:58Speaker 02

  No. I.

• 4:00Speaker 00

  Yeah, you definitely, something is happening.

• 4:03Speaker 02

  It's Chris.

• 4:04Speaker 00

  Can you just put your phone on silent?

• 4:06Speaker 02

  Yes, I can put my phone on silent. Um.

• 4:10Speaker 00

  Thank you.

• 4:10Speaker 02

  It's on silent.

• 4:17Speaker 00

  It's unexplainable. I'm Byrd Pinkerton. And we originally aired this episode a few years ago when we did a series on pregnancy and parenting. But we've recently had a bunch of people on the team become parents. So I have been thinking about pregnancy a lot. And especially about the idea that even though pregnancy is one of the most common experiences on earth, right? This thing that we all participate in in order to be alive. Pregnancy is still very mysterious. It's mysterious in ways that are amazing and inspiring, obviously, but also in ways that can hurt parents or at least confuse them.

• 5:01Speaker 00

  And so the story that I was telling my mom is kind of this perfect example of a lot of the things I learned about pregnancy over the course of my reporting. Like, it has got a wonder element, but it also has an element of just the frustrating reality that we are still very, very far from satisfying answers.

• 5:45Speaker 00

  All right. So let's just start with, with the basics here. This whole, like, idea of my giving you my cells, right? It's, it's actually a subset of something called chimerism, which you know what a chimer is, right?

• 6:02Speaker 02

  Yes, I do.

• 6:04Speaker 00

  You want to describe that for me?

• 6:07Speaker 02

  Well, it's like a, it's like a replication of the real thing.

• 6:12Speaker 00

  Uh, not exactly.

• 6:18Speaker 00

  So a chimera is like a, it's the mythical creature from like Greek myth. So you have like, it has like a lion head and like a snake tail and like a goat body.

• 6:29Speaker 02

  Okay.

• 6:30Speaker 00

  Like a griffon's a chimera, a sphinx, a manticore.

• 6:35Speaker 02

  It's the composite, right? Okay.

• 6:37Speaker 00

  Right. Let the record show that my mother did know what a chimera was and was unfairly put on the spot.

• 6:47Speaker 02

  Doesn't sound like your mother knew what a chimera was.

• 6:53Speaker 00

  So that is a chimera in myth. But to understand a chimera in biology and what it has to do with pregnancy, I reached out to Amy Boddy, who is this biologist at UC Santa Barbara. And Amy says that in biology, the definition of chimera is a little bit broader than in myth.

• 7:15Speaker 03

  It's multiple individuals existing in one host body.

• 7:20Speaker 00

  And so she was telling me that basically whenever you have a living thing that's made up of pieces of more than one individual, that's a chimera. So you can find them in plants, you can find them in animals, you can even find them in humans.

• 7:35Speaker 03

  Like if you see organ transplantation or something like that, where you have a large tissue, right, that's from someone that is a completely different individual, you can consider that person a chimera.

• 7:47Speaker 00

  So this is not like the goat lion hybrid version of a chimera, right? It's just bits of two genetically different people. But so technically, Mama, Amy was telling me that this process that you and I went through, where some of my cells left my body, kind of went into your body, that is considered chimerism on like a tiny scale. So they literally call it microchimera because you just have like a few cells. So cells from me, cells from my sister Chloe, and also potentially from any miscarriages that you might have had.

• 8:23Speaker 02

  So how many cells do I have from you?

• 8:26Speaker 00

  So according to Amy.

• 8:28Speaker 03

  It can be infrequently as one in a million cells, but we have 30 trillion cells in our body.

• 8:36Speaker 00

  So a trillion is like a million million, right? So if you're doing the math, could potentially be. 30 million cells from me floating around in you. Oh, yeah, but so, so some people have more, some people have fewer. They're actually, they're usually more during pregnancy and then your immune system kind of gets rid of a lot of them. But around the 1990s is when researchers started to realize that some cells were really sticking around in the parent long term, like potentially for the parent's whole life, which was surprising, right? And a lot of these cells are probably stem cells.

• 9:20Speaker 00

  So do you know what a stem cell is?

• 9:23Speaker 02

  Yeah, after my implosion with Chimera, I am not haphazarding again.

• 9:32Speaker 00

  Okay, so, so a stem cell is like the, the really basic cells that then develop into other tissues. So they're kind of like a, like jack of all trades, flexible cells that can turn into any kind of cell.

• 9:47Speaker 00

  So you can basically imagine like the fetus has these, these flexible cells, right? And then some of those cells travel into the placenta, which Amy was telling me is kind of like the main connector between the fetus and the parent.

• 10:01Speaker 03

  It's this super highway.

• 10:04Speaker 00

  So the, the fetus's cells sort of travel along this highway into the parent's body, hitching a ride in the circulatory system probably. And they finish their road trip eventually in the heart, say, or the lungs or the brain, sort of all over the body. And then they can reshape themselves into a heart cell or a lung cell or a brain cell, whatever they're around, and kind of braid themselves into that tissue. So they're doing work in the parent's body, even though genetically they're different from the cells around them.

• 10:42Speaker 02

  I'm intrigued, but I'm also puzzled. It basically opens up more questions than it even begins to answer.

• 10:53Speaker 00

  Welcome to the show.

• 10:56Speaker 00

  So, starting around the 1990s, these researchers were sort of like, all right, like, what is going on here? Like, if these cells are sticking around and becoming part of the body, are they affecting it in some way? Like, what are they doing?

• 11:14Speaker 03

  We don't know.

• 11:17Speaker 03

  But we have some ideas.

• 11:19Speaker 00

  First of all, Amy told me that it is very possible that, at least potentially, they are doing nothing.

• 11:27Speaker 03

  I have to admit it, even though I think there are some functional properties of these cells, but they could just be hanging out.

• 11:37Speaker 00

  Like, it is possible that my cells are just like the tchotchkes that you love to collect, right? Like, your little figurines that don't really do anything. They're just kind of there.

• 11:54Speaker 00

  It's possible that my cells are just the equivalent of that. Like, you have some tiny little cell-sized tchotchkes of me inside of you.

• 12:04Speaker 02

  I don't do, like, little things anymore. I bought this huge piece of granite the other day in Berne, and I liked it all the way home, which was kind of silly.

• 12:16Speaker 00

  You bought granite? Like, you can find granite on the ground.

• 12:20Speaker 02

  Well, but this was polished.

• 12:22Speaker 00

  Okay.

• 12:23Speaker 02

  Anyway, keep going.

• 12:25Speaker 00

  So, again, there is a possibility that these cells are just hanging out, like, polished granite. But researchers have some good reasons to think that these cells are potentially doing other things.

• 12:41Speaker 03

  There are some studies that show that these cells actually help the host body. And so there's ideas out there that, yeah, this is a good feature to have.

• 12:53Speaker 00

  So for example, there have been studies to look at if someone has a C-section.

• 12:59Speaker 03

  And they look at the tissue in the C-section.

• 13:04Speaker 00

  They've found cells from the baby in the parent's scar tissue, essentially.

• 13:12Speaker 03

  Suggesting that they are there helping heal the gestational parent's body.

• 13:18Speaker 02

  Uh huh.

• 13:19Speaker 00

  And again, it's possible that they're just sort of randomly there, right? Because as Amy was saying, like, these studies in humans aren't super firm evidence because we don't know what they would be doing to heal a body. It's not clear that there are necessarily lots more fetal cells like in the scar site than anywhere else in the body.

• 13:41Speaker 03

  And that's maybe one of the biggest criticisms of. They're just there. There's a few of them. You're just trying to find a purpose to this randomness of cells there.

• 13:51Speaker 00

  But if you just sort of step away from humans for a second, there is some more definitive research that has been done in mice. So in mice, they'll breed female mice with these special males so that some of their fetuses can create cells that fluoresce.

• 14:11Speaker 03

  It's like a glow-in-the-dark feature.

• 14:13Speaker 00

  And then the researchers can sort of dissect the mice or use machines to sort of track these glow-in-the-dark mouse fetus cells as they move through the mouse's parent body.

• 14:25Speaker 03

  If a mouse gets an ear injury, the fetal cells will migrate up to the tissue. It seems like they're primed to be able to go in and kind of help recover and heal the maternal body.

• 14:38Speaker 02

  Huh. That's

• 14:40Speaker 00

  Which is cool.

• 14:41Speaker 02

  That's cool.

• 14:44Speaker 00

  And again, like, something like that could also be happening in other mammals, including humans. So it's not just sort of like C-section scars, healing injuries. There's also been some research on how these cells that the parent gets from their fetus could potentially help with heart health.

• 15:04Speaker 03

  There was a mouse model where the heart was injured, and they saw these cells, these fetal cells, migrating to the injury specializing in helping repair.

• 15:19Speaker 00

  So this is in mice, but it would actually help explain a phenomenon that doctors have seen in humans, which is basically like, a lot of pregnant people develop heart issues. So your heart is actually doing like a huge workout during pregnancy. This will be no surprise to you, but you know, it's pumping a lot of blood. There's just like more of you and your body is working a lot harder. And so researchers have actually compared it to athletes who do long-distance sports.

• 15:48Speaker 03

  So you could just be pregnant and be like, I'm basically an endurance athlete. No wonder I hated it.

• 15:58Speaker 00

  But because the heart is doing this, this sort of nine-month-long workout, it makes sense that a lot of pregnant people develop problems with their heart during this time. What's interesting is that sometimes these problems just kind of fix themselves. Like, they go away and researchers aren't totally sure why. And some are wondering if the cells from the fetus actually help fix things. Like, if the cells from the fetus are traveling to the heart and giving it some kind of boost that could explain the sort of heart healing that is happening here.

• 16:36Speaker 03

  So it's quite fantastic, I think, in thinking about the coolest, weirdest biology.

• 16:44Speaker 00

  And again, like, this is just one example of the ways that researchers think that these cells could be helping a parent's body sort of heal or fix issues, right? So maybe, you know, my cells at some point helped heal something in you as well.

• 17:03Speaker 02

  I think your cells need to get their act together. Let's get going here.

• 17:10Speaker 00

  OK, I'll work on it. Nothing wrong with your heart, but I'll work on curing your various other ailments and diseases. Sorry. Sorry, I've been such a disappointment to you.

• 17:22Speaker 02

  You have not been a disappointment. Your cells are just, you know, let's get moving.

• 17:31Speaker 00

  Um, this feels like a perfect transition to the next thing here, which is that

• 17:38Speaker 00

  sometimes the parent-fetus cell relationship becomes strained in certain ways.

• 17:46Speaker 00

  Like any communication between parent and child. It's not all sort of heart healing and scar knitting. Sometimes the cells from the kid can be somewhat obnoxious.

• 17:57Speaker 02

  This is the playing less well with others.

• 18:00Speaker 00

  Yes. So up next, how these cells might actually play a role in a whole range of pretty serious diseases.

• 18:18Speaker 00

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• 21:45Speaker 00

  So, Mama, when I was in your womb, I gave you a bunch of my cells. This happens whenever there's a fetus inside a pregnant person for a while. And in this exchange, Amy Boddy says that there are trade offs.

• 22:02Speaker 03

  It might be helpful during pregnancy. It might be helpful in the postpartum period. But long term, there could be some trade offs where actually at some point, it can, it can lead to health complications.

• 22:16Speaker 00

  And one of the, the main complications that researchers have been exploring is related to autoimmune disease.

• 22:24Speaker 03

  Wow.

• 22:25Speaker 00

  So like, to be really clear from the get go, right? Like, this is all very much theoretical, right? It's something researchers are still trying to figure out. So I would not want anyone with sort of an autoimmune disease to immediately assume that it comes from myochymera or this like exchange of cells, right? But basically, the, the way that Amy explained it to me is that we have this immune system and, and its whole job is to sort of cruise around, check up on various cells and say like, is this me?

• 23:03Speaker 03

  Typically, your body recognizes self by specific markers on your cell that says, you know, like, hey, I am me.

• 23:11Speaker 00

  And it leaves those cells alone. But then if it comes across cells that don't look like itself.

• 23:17Speaker 03

  Then my immune system might say, no, let's get rid of this.

• 23:21Speaker 00

  But in an autoimmune disorder, the immune system kind of goes haywire, right? Like, it starts attacking cells that are part of the body, that are part of itself in some way. And that leads to sort of the, the swelling, the pain, tiredness, like a whole bunch of different issues that are associated with autoimmune disorders. And so the way that this is potentially linked to myochymera is It turns out that that people who have carried fetuses at some point in their lives do seem to be at higher risk for autoimmune diseases. The data that we have now focuses on women, but it shows that these diseases are significantly

• 24:02Speaker 00

  more likely to affect women as compared to men. And some studies have found that the chances of getting some of these diseases actually increases after women's reproductive years. So researchers were kind of looking at microchimera. And they were thinking like, okay, people who are getting pregnant are bringing kind of foreign cells into themselves that look a lot like them. Because usually, half our DNA comes from each of our parents. So these cells come in, they become part of the body, sort of part of the tissue. And then down the line, one scenario is that they do something that the body cells wouldn't usually do, right?

• 24:47Speaker 00

  Something more unique to the kid's cells. So maybe, for example, they're expressing a protein you've never seen before, then your immune system might say, hey, that's not self. We need to go ahead and and get rid of this. And that can, you know, elicit an autoimmune response. I don't know if we can call it autoimmune because that means self, right? Like, is it autoimmune? Because it's it's not attacking the self, it's attacking these foreign cells. And that's kind of the whole problem here, right? Like, these cells are both part of the parent's self and also genetically foreign.

• 25:30Speaker 00

  So maybe, and again, emphasis on maybe, this could be contributing to autoimmune diseases. Like, maybe these foreign, but not so foreign, cells are why the body starts attacking itself.

• 25:46Speaker 03

  Huh.

• 25:47Speaker 00

  And there have been a few studies to sort of look at people with autoimmune diseases to look for proof that this might be happening.

• 25:54Speaker 03

  There's a few different studies looking at individuals with autoimmune disease, and they find these fetal cells in the tissue.

• 26:01Speaker 00

  But, once again, like, these are mostly sort of correlations, like, we

• 26:08Speaker 00

  Saw these cells and we saw this problem. Maybe they're related.

• 26:12Speaker 03

  We don't know the root cause. We don't know if these individuals would have gone on to get autoimmune diseases anyways. And the cells again, just happen to be there.

• 26:23Speaker 00

  So like, there's still work to be done here to sort of tease this relationship out and figure out what's going on. But it is sort of one way, at least, that people think that some of these sort of cells from like fetuses could be causing issues.

• 26:40Speaker 02

  Okay, I am fascinated by this. I wish there were more information. But what, what an interesting possibility.

• 26:51Speaker 00

  I think, I think so too. Right? So, so there's this possibility, this possibility that they're involved in autoimmune diseases. And then the other possibility, which you are not going to like, is that these microchimera might also play a role in cancer.

• 27:14Speaker 02

  Lay it on, just lay it on.

• 27:16Speaker 00

  So, so basically, cancer is almost one of the best examples of maybe this is helpful, maybe this is harmful. Like, right now, it's just kind of deeply confusing. Amy was saying she actually got interested in microchimera when she was studying breast cancer. So she was sort of like, reading through these papers.

• 27:33Speaker 03

  And some women had a higher amounts of fetal cells in their body and were diagnosed with cancer.

• 27:42Speaker 00

  Which would suggest that there could be some kind of a connection again, or like a correlation, right? Like, more cells from the fetus, more cancer, potentially.

• 27:54Speaker 03

  But then there's other papers. This is where it gets really confusing. There's other studies showing that, no, actually, those cells might be in there trying to help fight the cancer. And actually, these cells are protective. And so it's a big, like, we don't know what they're doing. Are they fighting the tumor? Are they making, you know, the immune system more aggressive and making this cancer worse? And we, we don't know the answer to that.

• 28:22Speaker 00

  So, again, there, there are a lot of questions here, right? But if we can figure this stuff out, like, if we can figure out exactly the effects that microchimera have on our body in terms of cancer, or also autoimmune diseases, like,

• 28:38Speaker 00

  That could potentially be huge, right? Amy was saying that maybe we could figure out if people are high risk for certain issues and help them early, for example.

• 28:49Speaker 03

  The other exciting thing is some people are, again, seeing these potential fetal cells helping with wound healing. And the thought is that it could be a therapy as well, providing a boost of stem cells to actually help fight a disease or help heal.

• 29:08Speaker 00

  Right now, because this is all such a mystery, like, we are, we're still a very long way away from these kinds of applications, right? Which I guess kind of just left me wondering why, right? Like, why do we still have so many questions instead of answers here and know so little?

• 29:27Speaker 02

  That is a good question.

• 29:28Speaker 00

  Lee Nelson agrees with you.

• 29:30Speaker 04

  That's a good question.

• 29:32Speaker 00

  Lee Nelson is, is actually one of the researchers that I mentioned before who first started diving into microchimera in the 1990s. And she's been doing a lot of work for, for many decades on the autoimmune stuff specifically. So I asked her essentially, like, why we are still so far from answers.

• 29:54Speaker 04

  The most direct two answers to that are technical, so it's the techniques, and the other one is funding.

• 30:04Speaker 00

  Reproductive health in general is very underfunded, but this work is also just very hard from a technical perspective.

• 30:13Speaker 04

  The big challenge is very simple.

• 30:16Speaker 00

  There are all these little chimerical cells that are very hard to track. And, you know, you can put tracers in mice, like we mentioned before, but mice are not humans. Like, mouse pregnancy just looks different than human pregnancy, which could lead to different effects.

• 30:35Speaker 04

  I mean, routinely, mice are multiple gestations.

• 30:38Speaker 00

  They're routinely having, like, eight pups all at the same time, for example.

• 30:43Speaker 04

  I don't know anybody that's had eight or nine kids.

• 30:46Speaker 00

  And meanwhile, you can't like inject human fetuses with glow in the dark tracers, or cut up human parents in the same way as mice to see what's going on. And so as a result, when you're looking at some of these cells in human tissue.

• 31:03Speaker 04

  You can't really know both where it came from and where it went to and kind of everything about it.

• 31:09Speaker 00

  And then even if you do have sort of some tissue that you're looking at from a human, finding these cells isn't easy, right? It's a couple of cells in a million. And so it's kind of like looking for a needle in the haystack. If the needle looked like a lot like hay, right? Because it's actually got half the hay's DNA. And then, one extra wrinkle that I talked about with both Lee and Amy, but which I've sort of been saving for the end, is that microchimerism isn't just about fetuses passing cells to their parents. It's actually a lot more complicated because it goes both ways.

• 31:54Speaker 00

  So not only am I kind of giving you my cells, but when I was in your womb, you gave me some of your cells as well.

• 32:04Speaker 04

  Of course.

• 32:05Speaker 00

  Which means that you're not just sort of a chimera of me and my sister Chloe and any miscarriages that you might have had. You also have my grandmother, Muddy's, cells swimming around inside of you as well.

• 32:20Speaker 04

  That makes perfect sense. How far back to Sycamore?

• 32:25Speaker 00

  So it is also possible that your mom, so my grandmother, gave you some of your grandmother's cells. So any researcher sort of looking, Mama, at your tissue would be saying, is this cell from Anne Bird Platt? Or is it from her daughter Chloe? Or her daughter Bird? Or her mother? Or her grandmother? Or a miscarriage she had? Or like, what? And so Amy says it's just hard to parse.

• 32:56Speaker 03

  So we've been talking very simply about this because it is so complex that we, our minds can't even wrap around the fact that. There's actually multiple generations happening all at once.

• 33:09Speaker 00

  And so studying microchimera is so hard because you have to find just like a a few cells in a million, untangle this whole intergenerational jumble, and then figure out like what those cells are doing, what they're up to. And that's part of why this research is going so slowly.

• 33:32Speaker 03

  You're getting these like two of, you know, a thousand piece puzzle, right? You're like, I think it's a horse, but then you haven't seen, you know, the rest of the body or something like that.

• 33:50Speaker 00

  And I find it, I mean, I find it like, I guess there's something about it that,

• 33:56Speaker 00

  like, there, there might be things that we'd never fully understand here, right? Like, we are potentially never going to be able to completely untangle the way that like my cells and my sister's cells and

• 34:10Speaker 00

  the cells from your miscarriages have affected your body. Like, it's possible it's always going to remain kind of like a, like a parent-child relationship, right? Like, on a tiny scale, there'll be sort of pushing and pulling and hurting and healing and, you know, it's a relationship we can explore forever and never fully untangle.

• 34:34Speaker 02

  To be sure, but to me, the whole benefit of this kind of research is that what you know now, let's say you really, not you, one was really able to go into this into a lot more depth. There are always surprises. That's the reason everybody does research. They're always like, oh, we were looking for X and we found a whole different section of the alphabet. It strikes me as a good enough reason to pursue it.

• 35:11Speaker 00

  I'm beginning to realize where I came from. It's beginning to make sense that I have maybe some of your cells in my body.

• 35:21Speaker 02

  Yeah.

• 35:21Speaker 00

  And our brain. A question. Would you say I'm overall more of like a scar healing helper or an autoimmune disease trigger of a child?

• 35:33Speaker 02

  Oh, sweetheart, you are a scar healing helper.

• 35:39Speaker 00

  It's on the record.

• 35:42Speaker 02

  And I'm so happy you're here.

• 35:47Speaker 00

  I'm happy you're here, Mama.

• 35:51Speaker 00

  I love you.

• 35:51Speaker 02

  I love you. And I assume that's it. We're done?

• 35:57Speaker 00

  Yeah, I think that's it. I think I think we're done.

• 35:59Speaker 02

  Okay.

• 36:00Speaker 00

  Thank you for doing this.

• 36:01Speaker 02

  You're very welcome. In a separate space, I will bring you up to date on certain postal events coming your way soon. And you can bring me up to date on other events in your life.

• 36:27Speaker 00

  This episode was reported and produced by me, Byrd Pinkerton. It was edited by Brian Resnick and Catherine Wells, as well as Meredith Hoddinott, who runs the show. We had sound design and mixing from Christian Ayala, music from Noam Hassanfeld, Serena Solin checked our facts, and Mandy Nguyen is just really lovely to have nearby. I want to say a special thank you this episode to Lee Nelson, who sent so many articles that just really helped orient me and deepen my knowledge here. So if you want to read more about microchimera and autoimmune disorders, look up her body of research. I would also recommend the article that Amy Body co-authored in Bioessays in 2015.

• 37:13Speaker 00

  If you would like to support the show and the journalism that Vox does, we would love it if you would become a member. It is very easy to do. Just go to vox.com/members and you will get access to all of Vox's journalism, but you will also know that you are supporting all of Vox's journalism. And for those of you who have emailed to let us know that you signed up because of Unexplainable, thank you. And thank you to those of you who have left us a nice review on your podcast platform or told someone in your life about the show. You are all excellent. Unexplainable is part of the Vox Media Podcast Network, and we will be back very soon with another episode about everything that we do not yet know.