There is no more important universal problem in the Standard Model of elementary particles than the problem of mass and mixing flavor hierarchies.
The mainstream theoretical approach for treating it is to probe different group-symmetry flavor models. For decades, this math approach has not led to established flavor theory.
Is seems reasonable at this time to view flavor concept as related to new physics fundamental paradigm that should be firstly approached by simple means of semi-empirical phenomenology as exampled by physics history of e.g. quantum mechanics (Plank, Einstein, De-Broglie, Rutherford, Bohr, ...).