Personally, I think that "who" is somewhat beside the point. "What" and "how" are the more interesting questions. The answer to "who" just becomes "a specific

Personally, I think that "who" is somewhat beside the point. "What" and "how" are the more interesting questions. The answer to "who" just becomes "a specific instance of X" that perhaps has some low probability combination of minor characteristics compared to other Xs.