Ask my nephew he thinks making bed not manly
Guess he's never been in the military then? They put GREAT stock in making a bed in the military. Quite a manly place to work.
Making one's bed has practical purposes, rather than feminine or masculine reasons. In a humid climate when one isn't living in a climate controlled environment, pulling the "covers"...they are called that for a reason, as they cover things besides the human body and for mere warmth....over the bottom sheet and the pillow keeps these linens from becoming damp from the humid air. Damp and warm creates mold, mold is bad to be rubbing one's body all over and breathing in each night, so it's just good sense to make the bed.
In ANY climate, when one lives in housing that is more open than the citified, pussy footed type housing us softy panty waisted people all live in now, pulling the covers over the mattress and tucking them in keeps the creepy crawlies out of that area. When one goes to bed at night and visibility is lower, climbing into that bed could have either dire results or merely painful results if a creeping thing has taken up temporary lodging in the bed clothing if the bed has not been made nice and tight.
Another practical application for making the bed is that smooth, flat sheets are more comfortable on which to sleep than bunched up, wrinkled, wadded up bedding....if you've ever been flat on your back in a hospital bed for days on end, you'll understand why they used to be(and I say used to be...that side of nursing has long went by the wayside)such sticklers on proper bed making in the hospital. Even one crease in that sheet can start feeling like you are sleeping on a razor after awhile. Also, wadded up bedding in a hospital setting is the site for any number of germs, forgotten needles, or bodily fluids to be discovered later by someone who is already compromised in health and mobility, thus unable to easily avoid such hazards.
Your nephew, much like a couple of my own sons, are too young and inexperienced in life to understand the practical purposes for making a bed and also the sheer indulgent FEEL of sliding into a clean, smooth, softly made bed of clean linens that have been properly aired, smoothed and prepared for a restful night of sleep. When you get old you start to appreciate any and all things that promote restful sleep.
The military thought it was important enough all these many long years to teach this as a basic life skill and the more intelligent of those soldiers took that forward into their civilian life.