India, Jan. 29 -- Bill Gates is opening up about his childhood and adolescence in his upcoming memoir, Source Code, which will be the first in a series of autobiographical books from the Microsoft billionaire. In an exclusive interview with People magazine ahead of the memoir's release, Gates gave a glimpse into the heretofore unknown parts of his life that the book will shed some light on.

Among other things, the 69-year-old opened up about experimenting with alcohol and drugs as a teenager. Most of his stories involved his childhood friend Paul Allen, with whom he founded Microsoft in 1975.

In Source Code, Bill Gates speaks about trying LSD during senior skip day, a tradition in American high schools where the senior class bunks schoo...