Roxanne Khamsi

So part of this has to do with the fact that we are a collection of cells.

We all start as a single cell for the first 24 hours after we're conceived.

And then by the time we reach adulthood, we're around 30 to 40 trillion cells.

And that's not counting the 30 trillion cells in our gut microbiome that are microbial cells.

And there's a lot of turnover to maintain this mass of cells that we are.

Every time a cell divides, it's trying to copy its DNA and sometimes it makes errors.

And when it does make errors, those mutations, those DNA mistakes stick around in all the subsequent cells.

And on top of that, there's just like regular wear and tear that happens inside the cells of our bodies.

So DNA breaks.

And when that gets fixed, sometimes errors are introduced there as well.

So I think it's important to understand that the cell in my toe, for example, is not the same as the cell in my brain genetically.

And I like the idea of having a mosaic in mind because when we think about a mosaic, those pieces form a coherent whole.

But when you look at them individually and compare them, there are slight differences.

And I think that you can look at the human body the same way.

Our cells are different.

similar in that they're all working to make us, you know, sing a song or lift a spoon to our mouth.

But at the individual level, there are differences, and some of those differences can be meaningful.

It's a really interesting question, and I think this speaks to why I wrote this book.

I want people to understand that genetic disease is not always something that is inherited.

It's something that can spontaneously develop in us.