At 1,000-2,000 miles per year, even in paid business class, it will take a long time to earn a useful number of redeemable miles, so you shouldn't make decisions based on FF miles. Join a reasonable FF program for each alliance so that you never waste miles, but purchase tickets based on price and schedule. Sometimes you can use miles to purchase stuff like magazines or airline souvenirs before they expire.

BTW, I hope you realize that you're a lucky minor if your parents are willing to buy business class tickets for you.