Yesterday, I was standing at a market in Milan, picking apples. Bright green ones with a tang, or shiny yellow? I was almost decided — then something weird hit me: “I’m choosing.” Like a voice inside said — take this kind. Fine, but why this one? Why want something more than everything else? That feeling of choice felt like mine… until it started feeling oddly foreign.

Then a familiar fact popped up: there’s a whole civilization living inside me. More bacteria in my gut than my own cells. They have their own interests. They make almost all my serotonin, toss in dopamine, mix up GABA — the stuff I usually think of as mood, desire, anxiety. But it’s not my head cooking this up — it’s a lab somewhere deep in my belly.

It’s crazy how this isn’t just a metaphor, but a political drama with lobbyists. The bacteria deal directly with the brain: sending chemical messages through the vagus nerve (like smuggling on an inside market). Some love sugar and send out stuff that makes me crave chocolate; others prefer fiber and push me toward broccoli. I think “I want sweets” — but maybe that’s not my own wish, but a group text from sugar-loving microbes.

There’s another weird thing: if you transplant the microbiome from one body to another (they do this with mice), behavior traits come along with the bacteria. A calm mouse turns anxious after getting a depressed microbiome. Mood turns out to be contagious: catch a stranger’s bacteria — you change.

That means character isn’t just neurons and experience, but a symbiosis with trillions of tiny creatures inside me. So where does “I” end and this crowd begin? How far can I change my microbiome with diet or meds and still be me? Or after another round of probiotics, will I wake up someone else — and not even notice?

Personality looks like the result of a vote among different ecosystems inside the body. It’s not just me running the show top-down; it’s trillions shaping “me” bottom-up, fighting for resources, bargaining over moods and wants.

After that, feeling in control seems pretty shaky.

If I change these quiet tenants enough… will I still be myself?

I’m thinking about this between apple stands.

Who’s really picking the flavor now? Me or us?

And when was the last time a choice was truly mine?