What factors contribute to a person's handwriting being beautiful? Is it a natural talent or a skill that can be developed through practice?

I wish I knew. My handwriting and even printing are both atrocious and illegible. I have to use context to figure it out. My mother and two of her brothers have lovely handwriting. Like the pictures up around the classroom in elementary. Oddly, I could copy her signature exactly. Very handy. Could I learn to write legibly? 12 years didn't help so probably not.