  Considering a higher dimensional Lorentz group as the tangent symmetry, we
unify gravity and gauge interactions in a natural way. The spin connection of
the gauged Lorentz group is then responsible for both gravity and gauge fields,
and the action for the gauged fields becomes part of the spin curvature
squared. The realistic group which unifies all known particles and interactions
is the $SO(1,13)$ Lorentz group whose gauge part leads to $SO(10)$ grand
unified theory and contains double the number of required fermions in the
fundamental spinor representation. Mirror fermions could acquire mass utilizing
a mechanism employed for topological superconductors. Family unification could
be achieved by considering the $SO(1,21)$ Lorentz group.
