  A large proportion of transiting planetary systems appear to possess only a
single planet as opposed to multiple transiting planets. This excess of singles
is indicative of significant mutual inclinations existing within a large number
of planetary systems, but the origin of these misalignments is unclear.
Moreover, recent observational characterization reveals that mutual
inclinations tend to increase with proximity to the host star. These trends are
both consistent with the dynamical influence of a strong quadrupolar potential
arising from the host star during its early phase of rapid rotation, coupled
with a non-zero stellar obliquity. Here, we simulate a population of planetary
systems subject to the secular perturbation arising from a tilted, oblate host
star as it contracts and spins down subsequent to planet formation. We
demonstrate that this mechanism can reproduce the general increase in
planet-planet mutual inclinations with proximity to the host star, and
delineate a parameter space wherein the host star can drive dynamical
instabilities. We suggest that approximately 5-10\% of low-mass Kepler systems
are susceptible to this instability mechanism, suggesting that a significant
number of single-transiting planets may truly be intrinsically single. We also
report a novel connection between instability and stellar obliquity reduction
and make predictions that can be tested within upcoming TESS observations.
