Previous Post Quote: How can Henry Allen be named Jay Garrick on Earth 3? On Earth -1, Henry's mother's maiden name was Garrick. On Earth-2, either she never married her son's father, or was widowed or divorced and went back to using her maiden name. And instead of calling her son Henry, she named him Jason.

marriage to someone else, choosing another name, divorce, etc.

Parallel worlds, things are similar but not the same.

Remember the show SLIDERS? There was one time where they end up on an Earth where the main character's counter part was female. He was shocked and his traveling companion said "merely a difference in an X and a Y chromosome".