I believe my daughter may be the youngest. She's 14 and started when she was 11. She has won 7 championships along the way. She sets up her own game plans, does her own recruiting, and talks trash with me every day.
She was also my inspiration to create a tool that does some really cool stuff for this game - offensive and defensive game planning tools, recruiting tool, halftime adjustments tool, and even a post game analysis tool "just for fun."