advisor - Should your PhD students call you by your first name?

I've read at least one career advice essay that calls out asking your PhD students to call you by your first name as unprofessional.

My coworkers and I always called our PhD advisor by his first name, and a graduate student calling any professor by their last name, much less their own advisor, strikes my sensibilities as quaint and old-fashioned (undergraduates are a different story, of course).

What is the standard practice for this?