My sister and I go barefoot together all the time. We walk maybe 4 hours a day barefoot together. Yesterday we went on a path in some woods near our house. She was going first and as she sped ahead of me, i could clearly see the path she took. I asked her if there was anything unpleasant on the path. She replied with an honest no, just some roots, and as I went across, it was full of small thorn plants and freshly dropped holly leavs. After ouching my way though the path, I sat down where she was to pull out the 5 or 6 serious thorn and brush off the small stuff. She showed me her soles and had just has many deep thorns, but her soles were much tougher and thicker then mine. We go barefoot the same amount, why would she have tougher soles?
How old is your sister compared to your age? Also, maybe your sister walks differently- like maybe she runs faster and more often. There could also be differences in diet, hormones, genetics, etc. that could explain why your sister has tougher thicker soles than you do.
Oh who gives a flying fuck? All that matters is that your soles are tough enough for what you want to do.
What? This fella? Full of more bollocks than Comical Ali and who has an obsession with drawing pins? Who cares how tough your soles are? They just need to be tough enough for a bit of glass and some hot pavement at the end of the day.