RELATIONSHIP OF PEOPLE ACROSS AN INTERNATIONAL BORDER BASED ON AN ISONYMY ANALYSIS ACROSS THE GERMAN-DANISH FRONTIER

Using lists of names of male personal telephone subscribers, isonymy w as calculated within and between 29 contiguous areas in a north-to-sou th line extending 210 km south of Grindsted, Denmark. Each area shared some surname(s) with every other area. Isonymy was high across both t he present and past borders of Denmark with Germany and was consistent ly lower in areas beyond 160 km south of Grindsted. Relative isonymy b etween areas was also smaller on average south of the present border t han north of it, and smaller still for pairs of areas spanning the bor der. This is partly accounted for by decreases in isonymy with distanc e, but the slope of the logistic regression on distance is greater for the northern moiety than the southern one. Most of these findings can be traced to the influence of common surnames ending in 'sen', the di stribution of which tends to correlate highly with isonymy. Such surna mes tend to be of recent origin and to be very frequent and hence high ly polygenic. Thus much of the heterogeneity is explained by surname h istory rather than genetic heterogeneity.