Kroneld R
Department of Public Health, University of Turku, Finland.
Acta Genet Med Gemellol (Roma). 1988;37(2):143-6. doi: 10.1017/s0001566000004050.
A secular demographic study on the Iniö Island in SW Finland shows an even stronger decline of twinning rates than in the Aland Islands and the rest of the archipelago. Twinning rates in Iniö declined, in fact from about 30%, to less than 10%.