Starting with a general introduction to the flavour puzzle in the Standard Model (SM) and the flavour problem in generic new physics scenarios, I present a specific SM extension which is based on grand unification with Pati-Salam symmetry. The setup is supplemented with the idea of spontaneous flavour symmetry breaking which is mediated through flavon fields with renormalizable couplings to new heavy fermions. While new gauge bosons in this approach can be sufficiently heavy to be irrelevant at low energies, the fermionic partners of the SM fermions, in particular those for the third generation, can be relatively light and provide new sources of flavour violation. The size of the effects turns out to be constrained by the observed values of the SM Yukawa matrices, but in a way that is different from the standard minimal-flavour violation hypothesis. We determine characteristic deviations from the SM that could eventually be observed in future precision measurements in the quark and lepton sector.