Why are more men into diaper fetish than women? One reason is simply "mechanics." A man's sex organ is external and easily stimulated by wearing a diaper. In other words, it feels better to a man when he puts on a diaper. It touches the "right part."
A second reason more men engage in infantilism is that unfortunately a gender bias exists that stereotypes women as more adequate child-care providers, thus women actually change more baby diapers than men do. For women, it's not a thrill or a sexual turn-on because in reality, changing a baby's diaper day in and day out is messy, mundane, and necessary. Do it enough and it becomes a chore and not something erotic. (Babies don't decide when and if they'll wear diapers, and they can't change themselves).
Also, women are allowed to show a softer side if they choose to, and it's socially acceptable. Men are expected (or forced) to remain tough and strong. No wonder some men fantasize about returning to infancy and toddlerhood or imagine themselves being a little girl. It's so peaceful: No responsibility; no one depending on you to "be in charge of things," and everything is seemingly taken care of for you instead of you being the perpetual caregiver.
(Cute little girls melt your heart. Cute little boys break things).
And of course society has already laid the ground rules for things that don't belong together:
Water and electricity
Fire and gasoline
Diapers and sex
Baby June 1/21/2007