That's true whatever profession you choose. Professors might earn the distinction of tenure,but that doesn't guarantee that they'll keep putting in the long hours and late nights and have the passion and the drive to be great educators.
The same principle is true in your personal life. Being a parent is not just a matter of paying the bills, doing the bare minimum. It's not just bringing a child into the world that matters, but the acts of love and sacrifice it takes to raise and educate that child and give them opportunities.
It can happen to presidents as well. If you think about Abraham Lincoln and Millard Fillmore had the very same title. They were both presidents of the United States, but their tenure in office and their legacy could not be more different.