  In twin Higgs model, the Higgs boson mass is protected by a $Z_2$ symmetry.
The $Z_2$ symmetry needs to be broken either explicitly or spontaneously to
obtain misalignment between electroweak and new physics vacua. We propose a
novel $Z_2$ breaking mechanism, in which the $Z_2$ is spontaneously broken by
radiative corrections to the Higgs potential. Two twin Higgses with different
vacua are needed, and vacuum misalignment is realized by opposite but
comparable contributions from gauge and Yukawa interactions to the potential.
Due to fully radiative symmetry breaking, the Higgs sector is completely
determined by twin Higgs vacuum, Yukawa and gauge couplings. There are eight
pseudo-Goldstone bosons: the Higgs boson, inert doublet Higgs, and three twin
scalars. We show the 125 GeV Higgs mass and constraints from Higgs coupling
measurements could be satisfied.
