Are we allowed to ask Mathematics StackExchange users where they are from?

Are we allowed to ask Mathematics StackExchange users where they are from? (Of course that doesn't mean they have to answer that question) What do they do for work? and other questions, like how much time they put in usually to answer people's questions?

If this is Okay, how can I do so privately? I don't see a personal message option on the site.

I'm just curious.

• I've done it with users I've had numerous run-ins with, but deleted the comments afterwards. Oct 30 '15 at 3:30
• In a discussion related to election it was mentioned why some users (more specifically, some moderators) prefer to remain anonymous: Does a moderator candidate need to divulge the real name?. Oct 30 '15 at 4:37