Conversation so far:
What did George M. Cohan do in his early career?
George M. Cohan began writing original skits (over 150 of them) and songs for the family act in both vaudeville and minstrel shows while in his teens.
What were some of Cohan's skits?
George M. Cohan became a member of his parents’ act, reciting sentimental verse and performing a “buck and wing dance.” By age 11, he was writing comedy material

Question: Who did he write for?
Self-contained rewrite: Who did George M. Cohan write for in his teens?