Fun fact: "Mac" is the original Irish surname prefix meaning "son of," and "Mc" is the Anglicized form. McDonald = Son of Donald. As is usual, Irish names are patronymic meaning they're relating to the male's lineage. A daughter would be "Nic" (daughter of the son of) and wife "Mhic" (wife of the son of).

Then why so few "Nic"s and "Mhic"s? The Anglicized form isn't so particular about gender, so females use "Mac/Mc."

The "O'" prefix as in "O'Donnell" means "descendant of," along with its female variants.

https://en.wikipedia.org/wiki/Irish_name