For what its worth these are unlikely to be from seed, as apples are very unlikely to produce fruit which matches the variety of the parent.
All the apple varieties you eat have been cultivated from a single original specimen, via cuttings or (more likely) grafting onto a convenient root stock.
I feel this warrants more research for me.
The story is also similar for rootstock. Apples are naturally a fairly large tree, which isn't convenient for harvesting. The rootstocks that apples are typically grafted onto are genetic variants that don't grow as large.