It may be true that anyone can whistle, but I can only whistle by drawing air in, not by blowing air out.
I do several things backwards, including handwriting strokes and ice skate strokes. A friend told me today that approximately 20% of the population is born with the ability to be either right- or left-handed, and half of them just end up right-handed by chance. I'd wonder if I were part of that 10%, except that I can hardly do anything with my left hand. Still, it would explain all the backwards stuff.
Anyway, whistling. I can actually whistle pretty well by sucking in, but the breath cycle breaks down when I try to whistle a tune of any length. Many people have tried to teach me how to whistle the "normal" way, with no success.
As another birthday approaches, I realize that part of middle age is coming to terms with the things I will never be able to do. But what a feeling of accomplishment I'd have, even now, if I could figure it out.