Our training used Jeff Cooper's condition white, yellow, orange and red. For the right person, if practiced long enough it becomes natural.
While the Sheep, Wolf and Sheep Dog are pretty good ways of differentiating between the types, some will take offense, considering Sheep in particular objectionable, no one likes to be thought of as a Sheep and will reject the whole concept.
While some characteristics are, I believe, innate, some are not and many of us can and will be at least two and even a few I've known all three. I was definitely a Sheep for a couple of years for a variety of reasons until a Wolf again crossed my path; never again.