If opposites attract, why is my sister so pretty?

An early, playful evolutionary-biology musing (debated on a hike) on whether mates are chosen for genetic SIMILARITY or DISSIMILARITY. For dissimilarity: the MHC/sweaty-t-shirt result (Wedekind) and parasite-confounding. For similarity: separated-sibling attraction, a subliminal-opposite-sex-parent-flash study, spouses-as-similar-as-fraternal-twins (Rushton, whom Scott flags as dubious), and the 'ocular trauma test' (people marry people like themselves, not the maximally-distant !Kung). Lands inconclusively: attraction tracks similarity EXCEPT for MHC, which is 'weird and not parsimonious,' with no clean explanation.

Quality 62 · Strong. A thoughtful, engaging survey of a real puzzle, but slight, speculative, and deliberately unresolved — a casual idea-piece, not a developed contribution. Solid/Strong boundary. ⚠ REPLICATION CAVEAT (→Med): the argument leans on shaky mate-choice findings — the subliminal-opposite-sex-parent priming study and the contested MHC sweaty-t-shirt result (mixed replication).

Claude’s paradigm shift 48 · Moderate. Surveys known mate-choice findings; the similarity-except-MHC synthesis carries only modest novelty. Moderate.

Real-world impact 1 · Negligible. A niche evo-bio musing; no real-world effect. Negligible.