You are right. It is from his father. Had no idea he had a famous father or that he was a Junior. Or a third. It is confusing.
One of a line of businessmen named William H. Gates, and sometimes called William Gates Jr. in his career, he is now generally known as William Henry Gates Sr. due to the greater prominence of his son William H. Gates III (Bill Gates).
A heartfelt, deeply personal book,
Showing Up for Life shines a bright light on the values and principles that Bill Gates Sr. has learned over a lifetime of “showing up”—lessons that he learned growing up during the Great Depression, and that he instilled in his children and continues to practice on the world stage as the co-chair of the Bill & Melinda Gates Foundation.
“If You Born Poor,It is not your mistake,
but if you die poor,it is your mistake”
―
Bill Gates Sr.,
Showing Up for Life: Thoughts on the Gifts of a Lifetime
So we know the mindset he was instilled with.