Low probably
No one knows me inside and out, not even family members. My mother probably comes closest to it but there is quite a bit about me that she doesn't know. There are parts of me, I'm just not comfortable sharing with her, likely due to differences in socionic types. (I suspect she's an EII) Interestingly enough, there are things I would share with just about everyone *but* family members.
I'm an enneagram type 5 and type 5's are known to compartmentalize different parts of their lives. They will share part A of themselves with person X but not share part B. Meanwhile, they will share part B with person Y but not part A. Everyone see selected parts of them, but no one gets to see the whole picture. Also they will keep friends from separate realms in their life separate from each other so that friend X doesn't meet friend Y.
I tend to keep a large psychological distance with others until I feel more comfortable with them and they have earned my trust. I think for me, its a combination of learned behavior and type.