Mc: probably has a older brother or sister that runs the company or is at an obscenely higher level of business or something like that as a result mc was never needed. When some people needed him he felt the most happiest or something like that
Fmc: On the other hand, she has never felt a sense of self as she explained in a chapter nothing was hers everything of hers were her mothers. Her mother needs her. Thats what she thought.
These kinds of childhoods built the foundation for the way their personalities are now, is my theory.