I'm guessing you meant "real life" instead of "real time". It's tough to apply some OO concepts to things outside software. But since you mentioned a family tree, suppose I have a father and son. I ask the father to put on some music and he plays a 1940's big band CD. I ask the son to put on some music and he plays Green Day. I send them both the same message, they both understand the message, but they do different things in response.
If I ask the dog to put on some music he just tilts his head and looks at me funny. He doesn't understand the message, no polymorphism at work.
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi