X Chromosome K23

X Chromosome K23 is a modern, chromosome-specific admixture calculator that estimates regional ancestry from genetic variation on the X chromosome. Unlike autosomal calculators, this tool leverages the unique inheritance pattern of the X — transmitted from mothers to both sexes and from fathers only to daughters — to reveal sex-biased ancestry signals and historical demographic events that autosomes alone can miss. Designed for a global audience (researchers, genetic genealogists, students, and curious individuals), X Chromosome K23 reports proportions of X-linked ancestry across a broad set of global reference populations, enabling refined interpretation of maternal and paternal contributions over recent and deep time. What it analyzes: the calculator compares an individual’s X-chromosomal genotype against reference populations representing Africa, Europe, Asia, the Middle East, Oceania, and the Americas to estimate proportional ancestry. Because the X has a smaller effective population size and different recombination dynamics, it can show stronger signals of drift and localized ancestry, often enhancing resolution for female-lineage contributions. Insights users can gain: detect sex-biased admixture (for example, higher X ancestry from one region implies greater female contribution), contrast X vs autosomal ancestry to infer historical mating patterns, uncover regional affinities missed in autosomal analyses, and support genealogical hypotheses about maternal-line connections. The calculator also provides context about how demographic history, migration, and natural selection can shape X-chromosome patterns. Why it’s valuable: X Chromosome K23 complements autosomal and uniparental analyses by offering a different lens on ancestry that is particularly sensitive to female-mediated gene flow and recent demographic processes. It is a practical tool for those seeking a fuller, sex-aware picture of their genetic past, and for professionals exploring population histo