My twin brother and I are in our thirties and people still treat us like a unit, asking where the other one is, comparing us, making jokes about twin telepathy, and we've never talked about how it affects our individual identities or whether we collude in it because it's easier than explaining that we're actually quite different people.
More people experience this than they realize.
The ongoing negotiation of individual identity within a twin relationship that others persist in viewing as fundamentally merged or comparable.
“Where Are You with Sibling identity dynamics?”
If this sounds familiar, the Library can help you find the bigger picture.