Does everybody have an alter ego?

Yes..because actually,alter ego is someone's other self that we all have.A part of us that can either be seen/shown in situations that we are less conscious or half aware..Like a straight man who never knew he couldn't/wouldn't cry over anything until unexpected things happen in which he has no control of like the death of his child or whatever..

Alter ego can also be a person.Someone who has the same personality as you which is either a friend,a relative or simply someone you know.Often someone you share lots of compatibilities with naturally.

It is true we all are unique persons but we can surely see some similarities with others. And there is someone out there in the blue who is like you in many many ways,well,almost exact and can either be same sex or the opposite..