My older brother was the big influence on me riding a bike. I can remember sitting on my tricycle, watching him ride down the sidewalk and around the corner and realizing that the bicycle meant freedom. Later I borrowed a friend's Schwinn Pixie and taught myself to ride.
Both my parents got bikes later, when I was a teen. My mom didn't ride hers much, but my dad later commuted by bike, influenced by me in part I like to think. Their more important role was in support. They bought me bikes and had them fixed and replaced the ones what were stolen. They also gave me permission to ride to school by bike in the second grade, which was a major moment.