“My sister is a very HorseyPerson.”
I must not have properly explained my snarks - my bad.
Your sister is what I have always heard described as a “horse woman”. Your description of her indicated experience with, and understanding of, horses and their role/uses in society.
I used “HorseyPerson” in the manner one calls a National Park Service employee a “ParcPerson”.
My apologies for the confusion.