People have their own individual scent, why is that?

I’m talking about their natural body scent.

My girlfriend told me the other day that she could smell me on her one pillow. I asked her if it was my perfume, and she said, “no, your natural body scent” (which she loves), and ended up holding onto the pillow when she went to sleep. :)

Individual body scents, what’s that all about? (Jerry Seinfeld voice)