Environment variables location.

Hello everyone,
I am trying to figure out where all of my environment variables are getting set.
When I type env I get a whole list of them, about two pages full, yet I do not seem to find where they are initialized.
I checked all of my .profile .login and .cshrc files (I do not seem to have any .env files) and I cannot see them, where could I find them? Any tools I can use to know which files are getting run at start up? Maybe a command that will list them?

Thanks in advance to all of you.

/etc/profile

and some are built-in to the shell itself.