We were amazed to read Prior Lake Jake's lineage when we picked him up at the breeder's place. He could trace his bloodline back to a 1950s male who was featured on a Minnesota duck stamp and several other champions and one show dog. He had a broad curl down his back that was unique to his family. Most Goldens have rather fine, straight hair.
A lot of the field Goldens (the "little red dogs", a/k/a Swamp Collies) have rather coarse thick hair, with a wave down the back.
Labs are permitted to have a little wave down the spine, but my Chocolate overdoes it a bit - her hair down her back is almost (but not quite) curly.