Measure ancestry by shared drift

Instead of reporting admixture percentages that vary with reference choice, compare populations by shared genetic drift (f4/statistics and PCA) to ask whether one group is measurably closer to a migrant source than another. This reframes 'how much X ancestry' into a directional, robustness‑focused question that is less sensitive to model overfitting. — Shifting debate from contested admixture percentages to shared‑drift comparisons reduces misrepresentation and politicized misuse of genetic results in identity and migration debates.