Not just in the macro sense, but your guts have adapted to receive direct metabolic messages from the archaea and bacteria inside of you. It’s not inappropriate to say that those organisms attempt to modify your behavior on a low level as much as any functional group in your body does.
We have pretty clear evidence of “parasitic” behavioral modification via manipulation of metabolic processes (even assumedly high level behavior e.g. toxoplasmosis), but we don’t often think of the billions of other organisms inside of you. These organisms are actively attempting to modify their environment (aka, you) just as much as humans attempt to modify their own.