More correctly, all humans can have bias, but some humans are inherently better at critical analysis without applying bias. In fact, it's even possible to develop anti-bias, which would be a tendency to go against what one would intuit as natural bias. This is evident in the writings of some liberals, who will side against victims of violence if that violence was committed by a visible minority.

Bias in human thinking forms a continuum from virtually none to completely biased, and depends in large part on how closely the topic hits home. When asked, a bookworm might give a completely unbiased opinion on a particular video of a questionable goal in a soccer match, whereas the coach from either team would definitely not. I'm fond of throwing out anecdotes, so I'll lob another for the sport of it. I coached a junior hockey team many years ago, but fell out favor of come penalty time because I would witness the call and tell my players to go serve the penalty without squawking if they were obviously guilty. I was unable to enact bias even in a situation where bias is thoroughly ritual and expected. And perhaps my anti-bias is on display at this very moment given how civil I am being considering some of our previous engagements.