Not every comparison is conscious. You might never think the sentence you remind me of my brother about a friend, a partner, a colleague — and still be quietly running the comparison, using a template you assembled decades ago and haven't updated since.
The first draft gets written early, and it generalizes
John Bowlby's concept of the internal working model describes how a child's earliest close relationships establish a template for what closeness is and what to expect from people who occupy a similar role.1 A sibling relationship, especially one formed before you had much else to compare it to, is exactly the kind of relationship that can end up supplying that template — not because it was the healthiest one, but because it was early, and early relationships do disproportionate work in setting the baseline.
Memory organizes around a few dominant periods, not evenly
Martin Conway and Christopher Pleydell-Pearce's model of the self-memory system describes autobiographical memory as organized into lifetime periods — extended chapters, each anchored by a handful of dominant relationships and themes.2 A sibling from a formative period can become one of these anchors, which means later relationships don't just remind you of them occasionally — they get filed and interpreted in reference to that anchor by default. Conway's later work notes that memory continually serves the self's current goals rather than sitting neutrally in storage,3 which is part of why the comparison keeps reinforcing itself rather than fading with time.
It stays invisible until it's named
Because the anchor relationship isn't consciously present day to day, it operates as background — the water you're swimming in rather than a stated belief you could argue with. Most people who eventually notice this pattern report the same thing: they had never consciously thought "I compare everyone to my sibling" until they saw it laid out, across many different relationships, in their own writing.
Naming it doesn't undo it. It does turn an invisible default into something you can actually examine, which is a meaningfully different position to be in. See also how to journal about a difficult parent without making it about them and people, not topics, are the unit of a life.
- Bowlby, J. (1969). Attachment and Loss, Vol. 1: Attachment. New York: Basic Books.
- Conway, M. A., & Pleydell-Pearce, C. W. (2000). The construction of autobiographical memories in the self-memory system. Psychological Review, 107(2), 261–288.
- Conway, M. A. (2005). Memory and the self. Journal of Memory and Language, 53(4), 594–628.