I played football & wrestled in high school. I can truly say wrestling helps you in football in terms of teaching you to use leverage against your opponent. As for football helping you in wrestling, it reinforces the need to know what you are doing in terms of skill and strategy. You got to know how to block, tackle, understand the playbook, etc. in football. In wrestling, you got to know how to do single & double leg takedowns, how to use a cradle, half-nelson, etc. to pin an opponent, and how to get up after your opponent takes you down. If a young man in high school has the opportunity to compete in both sports, I'd encourage him to do so.