"Human beings are born with different capacities. If they are free, they are not equal. And if they are equal, they are not free." -- Aleksandr Solzhenitsyn
― Madeleine L'Engle, A Wrinkle in Time
The most obvious place to see this is looking at parents' economic outcomes versus their kids' development opportunities, but it doesn't even have to be generational.
If you have a sack of money (outcome), you automatically have many more options (opportunity) for creating a larger stack of money. Imagine a fair and random gambling game: Insolvent players are removed from the game, so the player with the deepest pockets at the beginning has the best opportunity of winning everything.