Experts and BHG readers answer.
growing apple trees from seed
"It is possible to grow an apple tree from the seed of a grocery store apple, but the fruit that develops on the seedling tree may not resemble the fruit that it came from. All apples are cross pollinated, so the pollen parent will be unknown. New apple varieties get started this way, but breeders grow out thousands of seedlings to get one that is good enough to introduce as a new variety.
If you decide to try it, the seed will need stratification (a cold, moist treatment) for at least 3 to 4 months before it will germinate. You may be able to do this naturally over winter, or by placing the potted seeds in a refrigerator for that length of time."