  In extra dimensions, the quark and lepton mass hierarchy can be reproduced
from the same order bulk mass parameters, and standard model fermion families
can be generated from one generation in the high dimensional space. We try to
explain the origin of the same order bulk mass parameters and address the
family replication puzzle simultaneously. We show that they correlate with each
other. We construct models that families are generated from extra dimensional
space, and in the meantime the bulk mass parameters of same order emerge
naturally. The interesting point is that the bulk mass parameters, which are in
same order, correspond to the eigenvalues of a Schr\"{o}dinger-like equation.
We also discuss the problem existing in this approach.
