Why do I know how to whistle (when others can't)?

Neither of my parents whistle. If they try really hard, my brothers can get one flat note out, or a very soft trill. I have always been a whistler, but I don’t recall learning or being around whistlers. The only relative I had who whistled constantly passed away when I was an infant. The majority of my friends cannot whistle. So why do I know how to whistle?

Do you know how to whistle? Why? Did you learn? Were you around whistlers? Have you always been a whistler?

Edit I do listen to a good deal of music with whistling, so it could be I picked up from there, but I’m still very curious about this as I get asked often by non-whistling friends how I know how to whistle.