I've noticed with cats - there are some I am very allergic to - others just mildly so -
Seems to depend on the cat. Length of hair did seem to be a factor, nor where they were living.
My Mom had several inside cats - I could pet Babe for hours - he was a long hair sweetheart - with minimal reaction - she had a short-hair black one - two strokes on him (when he got close enough!) and I was miserable for hours later.