While we talk about the boom as encompassing 1946 to 1964, demographers note that it really began mid-1946 and ended mid-1964. Harris, born in Oct 1964, can therefore fairly be described as Gen X.
Your book may cover this but, demographers notwithstanding, it’s hard to consider anyone who was still a teenager when MTV existed a Baby Boomer. Culturally, the children of ‘61-‘64 were the advance guard of Gen-X.