I was 6 and my grandparents got me and my 5 year old brother 20 inch wheeled bikes from Sears. We quickly mastered sideways power skids in the gravel.
A couple years later Stingrays were all the rage, so Dad brought home ape hanger bars and banana seats to convert our bikes. Best Dad Ever.
When he brought home Wammo wheelie bars Mom put her foot down and said no way. No problem, we quickly mastered proper wheelies.