3D geometry of cortical surface highly predicts individuals' genetic ancestry from West Africa, Europe, East Asia, and America. Cortical geometry retains ancestry information despite multiple migrations and admixtures. Geometry explains more ancestry variance than areal measures or total brain volume. Distinct regional folding and gyrification patterns characterize each ancestral lineage. Yoruban ancestry shows specific cortical surface morphing patterns. European ancestry correlates with prior findings on ancestral locations in Europe. East Asian ancestry displays unique cortical geometry signatures. American ancestry, shaped by admixture, remains predictable via cortical shape. Craniometric variations reflect population history mirrored in brain surface. Cortical surface contains richer ancestry signals than other neuroimaging metrics. Brain morphology shaped by migration and admixture retains genetic lineage info.