OS X: Where do environment variables get loaded from?

I have an env var that's being set(PYTHONPATH) whenever I open a new Bash shell, but I don't see any 开发者_如何转开发reference to the variable in ~/* or /etc/*. Where could this variable be set from?

It could be in ~/.bashrc, ~/.bash_profile, or ~/.MacOSX/environment.plist. * doesn't match files starting with . (hidden files).