In Young Frankenstein no one is really who they think they are. Frederick insists he's a "Fronkensteen" when he's really a Frankenstein. Elizabeth isn't as hands-off as she wants her fiancée to believe nor does Inga turn out to be the naïve milkmaid-looking ingénue-type she seems to be. And the monster isn't actually a monster at all. He's good (if not a good dancer)! By the end of the film, he and Frederick have swapped identities.
Questions About Identity
Why does Frederick not want to be associated with his own family? What makes him change his mind and embrace the Frankenstein name and tradition?
What does Inspector Kemp do to verify that Frederick is different from his ancestors?
How does the monster go from being monstrous to being civilized? How does Frederick also change in the process?
Why does Igor's hump keep moving all over the place?!
Chew on This
Frederick's denial of his family name is superficial at best. He is unconsciously following in his grandfather's footsteps by studying the human nervous system.
The monster is a monster because others see him as a monster. When others see him as a distinguished gentleman, he becomes one.