No you're correct. It does alter gene function.
You should pull out a real physiology book, it's actually a pretty complex procedure to describe. It's more than your typical steroid hormones (steroid binds to receptor, binds to DNA response element, etc.).
Here is a basic video version that answers the OP's original question:
http://highered.mcgraw-hill.com/olc/dl/120109/bio47.swf