Wild apples tend to be small and rather tart or bitter. Commercial varieties are not grown from seed but rather from cuttings from a mother tree somewhere. Planting Apple seeds results in apples resembling wild apples and not the cultivated variety the seeds come from.
>Many apples grow readily from seeds. However, more than with most perennial fruits, apples must be propagated asexually to obtain the sweetness and other desirable characteristics of the parent. This is because seedling apples are an example of "extreme heterozygotes", in that rather than inheriting genes from their parents to create a new apple with parental characteristics, they are instead significantly different from their parents, perhaps to compete with the many pests.[51] Triploid cultivars have an additional reproductive barrier in that 3 sets of chromosomes cannot be divided evenly during meiosis, yielding unequal segregation of the chromosomes (aneuploids). Even in the case when a triploid plant can produce a seed (apples are an example), it occurs infrequently, and seedlings rarely survive.[52]
>Apples do not breed true when planted as seeds, although cuttings can take root and breed true, and may live for a century, grafting is usually used. The rootstock used for the bottom of the graft can be selected to produce trees of a large variety of sizes, as well as changing the winter hardiness, insect and disease resistance, and soil preference of the resulting tree.
To clarify, the reason you are likely ending up with a wild apple phenotype is not because that is intrinsic to the nature of apples. Otherwise, new varieties could never be developed. Crabapples are used as pollinators for farmed apples since apples aren't self fertile, and you'll end up with a hybrid. If you've got the space and the time (in this case a lot of time), breeding is a great hobby for anyone.
Another factor is that apples from seed take a lot longer to fruit, and as you mentioned, you can really control the growth characteristics of the tree with the rootstock. Unlike mangoes, the rootstock can result in the same scion variety of apple growing into a 50 foot tree or a 5 foot shrub- thats a huge amount of control!
Even those will tend to bear more fruit when cross pollinated, and considering how common apples and crabapples are across the US, you granny Smith or golden delicious tree is still likely to get cross pollinated by a local decorative flowering crabapple. But yeah, I guess if you grew out golden delicious in a protected greenhouse and stabilized the variety over a few generations, you might have a true from seed apple variety at the end of it
Apple trees aren't inbred - the seeds will not grow into the same variety as the parent. Usually, store bought apples will have seeds that produce inferior fruit since crabapples are used as a pollinator (apples aren't really all that self fertile) - so the seeds are hybrid crabapple seeds. You'll still get a tree that produces fruit that makes a good jam, but not great eating apples. Its not true that you're guaranteed to get an inferior quality fruit from planting a seed - otherwise we wouldn't ever develop new varieties - but the conditions that made your supermarket apple happen will result in a eating apple/crabapple hybrid more often than not. Because they don't really self pollinate, you're not going to be able to create a breed of apple that produces offspring generally identical to the parent plant, so the only way to keep a variety going is to clone it with grafting techniques.
Stone fruits are especially easy and fun to propagate on the same tree such as this. You can do this at home and it’s fun! Beware the most vigorous variety will eventually take over the tree!
They are all hybrids and the offspring will not have the same gene mix as the parent. You’ll end up with apples with random mixes of characteristics from the grandparent apples.
Would you mind elaborating on that a bit?