Conversation so far:
When was Duff Mckagan born?
February 5, 1964.
What did Duff Mckagan accomplish in his early years?
At the age of 15, Duff McKagan formed the punk band the Vains.

Question: Who was in the band?
Self-contained rewrite: Who was in the band The Vains formed by Duff Mckagan.