My brother and I are twins but he's three inches taller and 40 pounds heavier, and people always assume he's older and more responsible even though we're literally the same age.
More people experience this than they realize.
He's observing how physical differences create social hierarchies even within family relationships, questioning the fairness of embodied assumptions.
“Where Are You with Body as identity — physical self-concept?”
If this sounds familiar, the Library can help you find the bigger picture.