In our previous studies on nasal conditioning, we observed a large variability among individuals to condition inspired air. Although we previously investigated various physiologic parameters (age, sex, nasal mucosal temperature, heart rate, blood pressure and nasal volume) that might underlie these differences, we have been unable to explain this variability. Many proteins and molecules are involved in water transport, which are under genetic control and could affect nasal conditioning. In this study, we hypothesized that familial factors may contribute to the differences in nasal conditioning capacity (NCC). We performed a prospective study of 47 sibling pairs. Cold dry air (CDA) was delivered to the nose and the total water gradient (TWG) was calculated to determine the NCC. We found a highly significant intraclass correlation of 0.53 (p<0.0001) between sibling pairs for the TWG. These results suggest that there is a familial basis for nasal conditioning and a large enough genetic component to search for genes explaining the observed correlation.