Nature Human Behaviour, Published online: 18 August 2026; doi:10.1038/s41562-026-02555-9 We developed a method that detects the genetic footprint of partner choice without requiring the input of partners’ genotypes. Instead, it reconstructs maternal and paternal genomes within a single individual, capturing half of each parental genome. Applied to nearly half a million people in the UK and Estonia, our method reveals partner similarity that has intensified for height and educational attainment over the past six decades.