Abstract
Male mouse pups exhibit elevated preference for novelty relative to their sisters. The testes of pups secrete high levels of Müllerian inhibiting substance (MIS, anti-Müllerian hormone), with neurons being a target of this hormone. We report here that
Mis
+/+ male pups exhibit novelty preference, but their
Mis
−/− brothers and
Mis
+/+ sisters do not. This suggests that MIS is one of the determinants of “boy”-specific behavior.