I've told my mother. My father is far too arrogant and if he were to find out he'd get me exorcised.
The only reason I had told my mother is because it was directly after a time when psychosis was giving me love kisses. I felt she needed to know what was happening inside my head and so I spilled out quite a bit, including my tulpa. Her initial response was "So, do you share time in control 60-40, or more towards 90-10?".
Needless to say, it didn't go over well. I had to slowly convince her that we couldn't switch like that (Never mentioning that we might be able to in the future) and had to get her to realize my tulpa is a good thing and not some possessive demon. After the psychiatrist, I showed her tulpa.info and her first question was: "There's hallucinations! Didn't that concern you?"
It's very, very awkward and I can only suggest against telling family about tulpas. My mother has never brought the subject up since I showed her the site and I just assume she's blocked it out. It's not worth it.