If you believe you do not have hidden biases--hidden from yourself, read one of these books and be amazed.
On Being Certain by Robert Burton
Mistakes Were Made (But Not by Me): Why We Justify Foolish Beliefs, Bad Decisions,, and Hurtful Acts by Carol Travis
Blind spot: Hidden Biases of Good People by Mahzarin R. Banaji
Pathological Altruism edited by Barbara Oakley
Predictably Irrational by Dan Ariely