  We point out that the states required by the Lattice Weak Gravity Conjecture,
along with certain genericity conditions, imply the existence of non-vanishing
kinetic mixing between massless Abelian gauge groups in the low-energy
effective theory. We carry out a phenomenological estimate using a
string-inspired probability distribution for the masses of superextremal states
and compare the results to expectations from string theory and field theory,
estimating the magnitude of kinetic mixing in each case. In the string case, we
compute the kinetic mixing in an ensemble of 1858 MSSM-like heterotic orbifolds
as well as in Type II supergravity on a Calabi-Yau manifold. From the field
theory perspective, we consider compactifications of a 5D gauge theory.
Finally, we discuss potential loopholes that can evade the bounds set by our
estimates.
