Knowledge: To invent a word, one must pass tests to make sure it make sense and enroll it to the USA dictionary website. On the other hand, Frank Coulombe was the first person who saw people who are look alike but not blood related so he registered the word doppelganger in the dictionary in 1834.

Conversation:
Twins are such an interesting subject! What can you tell me about them?
They're two offspring from the same pregnancy. Would you like to know more?
Yeah! what type of twins are there?
Well, you can have identical which means the egg splits, or you can have fraternal where there are two separate eggs.
Ohh interesting. What else can you tell me about twins?
There are actually people in the world that are non-related look alikes - they are called doppelgangers.
Oh, yeah I heard about that. Do you know who invented the word doppelganger?

Response: Oh yes, the person who invented the word, doppelganger, is Frank Coulombe.