hygiene

So... could someone please explain to me *why* fen are more likely to have problems maintaining adequate bodily hygiene than other people? I outgrew the not-showering-enough habit by the time I was 14 or so (though a friend's mom had to tell me I needed deoderant, probably a year after I actually started needing it.) I don't especially understand why people would choose not to stay clean, when the means for becoming clean are available to almost everyone....