What does it mean to breed 'True'? Breeding True means the fry will have certain traits no matter what. An example of this is butterfly. If you spawn a fish that carries BF all the fry will have it or carry the gene.
There are a lot of genes that don't breed true. I'll use the HS (halfsun) as an example.
Generation 1 HM X CT: Some or all will show the comb tail trait. Some will also have a HM span.
Second spawn Bro X Sis: There will be a mix. Like HMs with NO fringes to CTs with EXTRA fringes.
Third spawn: Same as above except less CTs and more HMs.
I can't really go farther since I never spawned more than three generations of the Red Crusaders.
A thing about buying expensive bettas: your NOT buying the fish. your buying the genetics.