My wife found this from a 1950's magazine.
1. Always call him for practice when the ball game is going best; call in a loud, demanding voice so his friends will feel sorry for him.
2. Insist he practice the most uninteresting music the longest. “You can’t learn much by playing tunes.”
3. Stop him if he plays anything for fun or any music other than his lesson. “Music is serious.”
4. Never help him with his practicing. “I just don’t have the time.”
5. Add another hour of practice when he has been naughty, or when he does not mind you. “That will teach him!”
6. Call loudly from kitchen or basement each time he makes a mistake. Add a punch line, such as, “If you can’t do better than that, give it up.”
7. Insist he never practice when (a) father is home, (b) baby is taking a nap, (c) Susie is looking at TV, or (d) mother is tired.
8. Pay no attention to his music making. “I don’t care whether he practices or not. It is entirely up to him.”
9. Don’t let him play for his friends or anyone else until he can really play. “After two or three years he’ll be able to surprise them.”
10. Take him unawares the first time you want him to play for someone and ask him in front of everybody to play “something.” If he refuses, insist that he play; if he still refuses, announce that he’s through with music.
11. Apologize for his poor performance when he does play for others.
12. Never compliment him on his playing. He may get an inflated ego.
13. Keep him away from concerts and recitals until he’s old enough, and don’t take him unless he can play well enough to “appreciate” it.
14. Use an old wreck of an instrument instead of buying a new one. “No sense wasting money until he plays real well.”
15. Don’t tune the piano. “He needs to learn to finger the keys; it doesn’t matter how it sounds.”
16. Threaten, periodically, to stop his lessons unless: (a) he plays better than so-and-so, (b) he makes better grades in school, (c) he makes his bed each morning, (d) he treats his parents with more respect.
17. Lay down the law forcefully, just as your parents did with you (even though you quit playing at the first opportunity).