Nostalgia! - Where does it fit in the creative process? People are the product of their influences. For a lot of us these happen when we're growing up and learning about the world for the first time. As you get older the things you experience don't make as much impact, simply because your brain has already had most of its “first times” and it's already learned enough about the world to be fully functional and independent.
“Nostalgia” is strongest when you harken back to those formative experiences.