TLDR: Don't ask for irrelevant information. It helps you make a biased decision.

Asking about hobbies needlessly introduces bias into your interview process. The hobby(ies) of candidates is completely irrelevant. One may respond saying "oh, but we just want to make small talk," but it's that small talk that is the precursor to bias to begin with. All things being equal, you would prefer someone more similar to you.

> Our findings indicate that people are more willing to give to, share an office with, commute with, and work on a critical project critical to their advancement with individuals who are similar to them selves (Self) along a particular identity dimension than with individuals who are dis similar (Other) [1]

[1] http://conf.som.yale.edu/obsummer07/PaperBen-NerKramer.pdf