Small holes in a T-shirt: why they always appear in the same place

work surface while cooking or

working creates friction in exactly that spot. If there is also a trouser button or belt behind it, the fabric can be subjected to extra stress. (BabyMac)

This could explain why the holes always appear at approximately the same height in some people.

Why are thin  T-shirts particularly affected by this?
Many people who suffer from it report that light cotton shirts and thin, blended fabrics are especially susceptible. Thicker or sturdier  garments seem to be less prone in some cases. (BabyMac)