  We study electromagnetic as well as strong isospin breaking effects in the
isospin mass splittings of light pseudoscalar and vector mesons. To this end we
employ a coupled system of quark Dyson-Schwinger and meson Bethe-Salpeter
equations whose interaction kernels contain gluon, pion and photon exchange
interactions. In bound states, QCD-induced isospin breaking is manifest on
different levels. On the one hand, a different explicit up- and down-quark mass
directly affects the propagators of the constituent quarks. On the other hand,
it leads to different interaction kernels within the isospin multiplets. In
addition, electromagnetic isospin breaking is induced via a photon exchange
diagram. Using the kaon iso-doublet and the charged pion masses as input to
determine the up, down and strange quark masses we find for the pion, kaon and
rho meson mass splittings different patterns each. In particular, our results
provide evidence that the effects from two sources of mass splittings, the
different quark masses and the different quark charges, do not add up linearly.
