Difference in contagious yawning between susceptible men and women: why not?

In their commentary, Gallup & Massen [1] criticize the fact that we did not consider 'more than a dozen' previous publications which did not report gender differences in human contagious yawning. We thank the authors for pointing out this issue and for giving us the possibility to provide a brief explanation on some aspects that are not as obvious as we thought.