Surname repetition and isonymy in northeastern Hungarian marriages.

The repeated-pair (RP) approach to surnames in married couples is a measure of population subdivision resulting from the influence of lineagelike behavior in mate choice. An excess of RP over random RP implies limitations in mate choice and a reduction of genetic variability. Here we apply the RP method to data from the rural populations of Csaroda, Tiszaadony, and Tiszavid in northeastern Hungary. The results indicate small differences between RP and random RP for Tiszavid and somewhat larger differences for Tiszaadony and Csaroda. The excess of RP over random RP in Tiszavid, however, derives primarily from marriages simultaneously isonymous and repeating in only one lineage. The discrepancy between RP and random RP implies a small reduction in genetic variability.