I wouldn't go that far, but there are many studies that have looked at the genetic (biological) basis for brain function/behavior [0]. Once you're at the level of gene expression, which some of those studies go into, you're at a level of acetylation, methylation, etc., which is easily categorized as chemistry.

The bigger argument I get into with coworkers is the blurry line between brain function/behavior stuff and psychology.

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3030621/

> by that same token, all of psychology is also physics.

Yes, it is, which would be relevant if someone suggested there was no physical explanation for a psychological phenomenon (which is, in fact, what they are usually claiming when they claim it is not biological.)

Some people, pedantically, agree xD

https://xkcd.com/435/