Can anyone be fast? or is it just something you're either born with or you're not?

If anyone can have speed on the feet, is it just developed through a lot of drilling? Weights? I'm assuming that with a good set up and a lot of drilling the actual shot would help more than weights, but explosive lifts and plyos would help some I'd imagine. I see people like John Smith absolutely dominate with his quickness, and I've read he shadow wrestled a lot and drilled a lot. So is it just natural to be that quick or can it be developed?