Doctor here (family medicine). I self diagnose most things, but for my 1 year old daughter I decided a while ago that I don't want to do that for her. So her pediatrician doesn't know I'm a doctor – I never told her. I want her to treat me like any other parent, and explain everything to me like I'm 5 years old. I'm afraid of of being too nonchalant with my daughter's health that I'll miss something (or the doctor assuming I know more than I really do).
It's actually a strategy I've adopted since on myself- if I go to a doctor (say a gynecologist for a routine check up) I sometimes just don't say what I do so I can legitimacy ask dumb questions about things that I should really know- or so that the other doctor won't leave out important info that they assume I know for fear of insulting me.
On the other hand, my regular doctors do know, such as the gynecologist who saw me through my pregnancies, and that enables more complex and nuanced disscusions about health decisions- as in debating questions and giving me options that he wouldn't necessarily do with it he patients, bc he can be sure I understand the medical pros and cons well once I'm given a basic explanation.