Verrrry strange! And interesting, for us pedants(or in my case, wannabe pedant). I'm thinking that English may have used a different word there, but it just degenerated into "whose" along with the loss of the rest of the case system. I mean, do you really think that back in the day they used just one word for "who" as a direct and indirect object? Which is why I really don't like the word "whom", BTW. So imprecise.