Take a pic of the bottom of the tree and where the varieties vary.
IF there's a grafting scar, its a real crap shoot. IF it is a grafted tree, but was grafted too high, you can have both rootstock and grafted variety there.
I have not succesfully grew a tree from seed, but I read on here a few things.
Score the seed a bit, put it on the ground in the fall, cover it with a bit of sand, and cover iwith a window screen to prevent critters from messing with it.