I have grown more then 50 sugar apples from seed and so far they grow true for me
I have 2 green Na Dai next to each other that I grew from seed and the fruit is identical.
I also grew two Na Dais that were from the same batch of seeds and they were terrible
tasteless fruit and I dug them up.
I grew up 10 big red seeds and all 10 produce red fruit that is not chewy. I grew 2 Isan indigos from seed
and they both produce chewy red fruit. I grew 20 Thai Lessard and they have produced green non chewy fruit.
The fruit varies from year to year for intance this year the Na Dais were smaller and seedier, but
there was allot more fruit I should have thinned them. Last year they were close to 2 pounds.
If you pollinate the trees with other pollen you could get variation in the seedlings but maybe
since I don't hand pollinate I haven't seen any weird offspring. I currently have 4 different red types
I grew from seed including Big Red, Isan Indigo, and two different Thai types.
I really like the Berry flavor and if I was going to compost anything it would have been the green
chewy types but instead I gave most of them away to people and they told me they enjoyed them.
So far I have never produced anything that was not like the parent of the seed. I did get some
Big Eye seeds and will keep several to evaluate, I appreciate Mike T info on their variability.