His parents believed that the priesthood was his 'destiny'. [=that he would or should become a priest because fate or God intended it]
They were living in a time when expansion to the Pacific was regarded by many people as the 'Manifest Destiny' of the United States.
She felt that 'destiny' [='fate'] had decided that she would one day be President.
(..) I'm not supposed to, so I'll just leave it here for you. I don't know if mama was right or if it's Lieutenant Dan. I don't know if we each have a destiny, or if we're all just floating around accidental-like on a breeze. But I think maybe it's both. Maybe both is happening at the same time. (..)1994 Forrest Gump
(..) I didn't know it, but I was destined to be your mama. - I did the best I could. - You did good. Well, I happen to believe you make your own destiny. You have to do the best with what God gave you. What's my destiny, Mama? You're going to have to figure that out for yourself. You never know (..)1994 Forrest Gump