Most singers learn to sing by imitating other singers, as another thread points out. As time goes by, they blend the style of others into something that becomes their own style.

Any idea where yours comes from?

I think that the greatest influences on my singing were jazz and rhythm and blues singers. Being playful with phrasing and melody comes from jazz and feeling the rhythm in a song comes from rhythm and blues. There were several singers whose records I sang along with for so many years that I know they have a lot to do with my style. Before I heard much rhythm and blues, Frank Sinatra was the singer I was probably most influenced by. When the first rhythm and blues recordings became popular, from the groups to Fats Domino, Gene Vincent and Chuck Berry, I sang along with those records for countless hours, and the phrasing became part of my singing. Because I came to folk music even later, I think that it had the least influence on my singing (other than blues and black gospel, which just built on rhythm and blues influences.) When I first heard traditional folk music, I tried my hardest to shed all traces of vibrato and inflection. I wanted to sound 70 years old and toothless. Time took care of the 70 years old part (and I still have my teeth.) Gumming songs sounded sooo authentic to me.)

Finally, I left that southern mountain, nasal style of singing behind and all the rhythm and blues influences became a natural part of how I sing.

All this said, the one singer who probably influenced me more than anyone was Clancy Hayes, who sang traditional jazz with Bob Scobey.
Clancy sang a lot of songs that cross over into the edges of folk music, like Long Gone, and Sailing Down to Chesapeake Bay, but the lasting influence in his singing was that he just had such a Hell of a good time singing. He let the song sing him, let the rhythm take him where it wanted to go and savored the words.

And eventually, we all end up sounding like ourselves.

Jerry