What is a sense of balance?

What constitutes one’s balance? If someone has an exceptional sense of balance, what specific traits do they possess?

It’s something that can be learned/trained, but it must also be genetic. I’ve been in martial arts for years and my balance in kicks, throws, shoots, punches, weaponry is trained and precise. But… and this is what prompted this question… sometimes when I walk I just lose my balance to either side. Naturally, I think I’m abnormally clumsy.

Why?

When you’re doing martial arts, you’re concentrating on balance. When you’re just walking, you’re not.

The key term you’d want to search on is “proprioception”, which is basically the sense that tells you where your various body parts are–not something you think about much, but man, would it suck to lose it.