If you write under a pen name, who knows your real identity?

Since you write under a pen name, which people in your life know that you’re a writer?
When I started writing I had to make a decision about how “out” I wanted to be. I decided to use a pen name to make sure my academic research and my mystery stories didn’t show up together in the same search. On the other hand, I wanted to be able to do in-person talks and book signings and have an author photo. So I settled on being pseudonymous, rather than anonymous. My family and friends, some of my work colleagues, and one or two of my students know my secret identity.