TL;DR
Kids produce a tonne of bodily effluvia, and parents have to deal with all of it. It turns out this experience helps to inoculate parents not just against soiled nappies, but also non-child-related categories of yuck.
Disgust habituation
Anyone has spent more than five minutes around young children knows it: kids are gross. We’ve even scientifically studied this in the past! (Go read this paper if you’re curious.) This presents a problem to parents, who literally have to deal with their shit.
To study the effects of this endless barrage of poo, our team produced and documented years worth of infant and toddler nappies. We then presented parents and a non-parent control group with the photos. Unsurprisingly, the controls tended to look away. However, parents showed little to no disgust avoidance. This even extended to photos that were not of nappies, but of bodily effluvia that were not directly related to children.
The one exception to this is among parents whose children have not yet started weaning. Those parents are as grossed out, if not slightly more, than non-parents. (This was even true for those who already had an older child!) Maybe they’re being extra careful due to their infant’s sensitive state?
The main lesson here is that, given long enough time, humans habituate to disgust elicitors. This nicely aligns with e.g. Charlotte Edgar’s work on generalised disgust habituation in medical professionals, albeit without the potential for people with low disgust sensitivity to self-select into ‘dirty jobs’.
Press coverage
Several media outlets covered the study, including the magazine New Scientist, NPR’s podcast and radio show Short Wave, and various others (including in French, German, and Mandarin).