This is one of those cases where it is important to remember that possessive pronouns never take apostrophes, even though possessive nouns do (see it’s/its). “Who’s” always and forever means only “who is,” as in “Who’s that guy with the droopy mustache?” or “who has,” as in “Who’s been eating my porridge?” “Whose” is the possessive form of “who” and is used as follows: “Whose dirty socks are these on the breakfast table?”
Somehow I lost my "Whose" in a few of my recent postings. Mrs. Beach, primary teacher extraordinaire, kindly reminded me of my grammar and I'm back on track and quickly covering my egregious errors as she finds them in my writing. Thank you Mrs. Beach. I will try to improve in the future.
P.S. This is one sure way of keeping Mrs. Beach as an attentive reader!