  The flavour puzzle remains as one of the most intriguing enigmas of particle
physics. In this thesis, we propose and study theories of flavour which
generically hint to a multi-scale origin of flavour. First we explore the idea
of fermiophobic models and messenger dominance, where the chiral fermions of
the Standard Model are uncharged under (part of) an extended gauge symmetry,
which also forbids Yukawa couplings for chiral fermions. These are generated
effectively due to the presence of hierarchically heavy messengers, including
vector-like fermions and/or heavy Higgs doublets. Simultaneously, this
mechanism generates effective couplings of chiral fermions to the gauge bosons
of the extended symmetry, leading to a predictive phenomenology connected to
the origin of flavour hierarchies. We present two models of this kind, based on
gauge $U(1)$ and twin Pati-Salam symmetries, that have implications for low
energy flavour anomalies. Secondly, we study the framework of flavour
deconstruction, where the Standard Model emerges from a non-universal gauge
theory that contains a separate gauge factor for each fermion family. We argue
that one of the most simple ways to achieve this is by assigning a separate
gauge hypercharge to each fermion family, denoted as the "tri-hypercharge"
theory. If the SM Higgs only carries third family hypercharge, then only the
third family is massive at renormalisable level, and light families get their
mass from higher dimensional operators. Finally, we propose a gauge unified
origin for gauge non-universal frameworks such as the aforementioned
tri-hypercharge theory. The model assigns a separate $SU(5)$ group to each
fermion family. However, assuming that the three $SU(5)$ groups are related by
a cyclic permutation symmetry $\mathbb{Z}_{3}$, then the model is described by
a single gauge coupling in the ultraviolet, despite $SU(5)^{3}$ being a
non-simple group.
