I can whistle, but it's harder for me than it should be. More often than not it's inconsistent, so there's things like I can whistle some of the Spring portion of Vivaldi's Four Seasons but it takes a while to get the sound of whistling down before I do.
I can whistle pretty well. It's weird to hear that people cannot whistle, but thinking about it, I don't know how I whistle. LIke, what does my tongue do? Does my throat flex a certain way? I have no idea.
I learned how to whistle in late elementary/early middle school shortly after my brother learned. He annoyed the heck out of my family after getting good at it, and I guess seeing and hearing him whistle so much eventually resulted in me picking up the skill.
I can whistle to pitches, but it generally takes time for me to perfect the tune. I also don’t dare to practice because I don’t like making noise, which is probably why I’m not better at it.