  The problem of families, "Why are there three families of fermions?", is a
long awaited question to be answered within a reasonable framework. We propose
anti-SU($N$) groups for the unification of families in grand unification (GUT)
groups, where the separation of color and weak gauge groups in the GUT is
achieved by antisymmetric tensor Brout-Englert-Higgs boson instead of an
adjoint representation. Theories of anti-SU($N$)'s are proposed for the
unification of families. The minimal model is found as \antiSD \, GUT with the
fermion representation [3]+2[2]+8[\bar-1]. We present an example in a Z(12-I)
orbifold compactification, where the missing partner mechanism is also
realized.
