Impaired nest building in Df(h15q13)−/− mice. Maximal score is 8 (see Materials and Methods). n=6–10 females for each genotype. Two-way ANOVA, no significant interaction between time and genotype. Main effect of time (P<0.0001) and genotype (P<0.0001). Tukey’s multiple comparisons indicated. Data presented as mean±s.e.m. ***P<0.001. ANOVA, analysis of variance; WT, wildtype.