An investigation of the high twinning rate in the Republic of Ireland.

Europe Austria (1968) 1,168 9-3 Bulgaria (1964) 870 6-7 Czechoslovakia (1963) 2,260 9-7 Denmark (1963) 909 11*1 England and Wales (1968) 8,184 10-0 East Germany (1967) 1,234 4-9 Irish Republic (1959) 892 15-1 (1968) 821 13e6 Northern Ireland (1968) 351 10-8 Italy (1965) 5,560 5-6 Netherlands (1966) 1,340 5-6 Norway (1967) 328 4-9 Poland (1966) 5,784 11-0 Portugal (1968) 992 5-1 Romania (1965) 1,250 4-5 Scotland (1968) 1,006 10-6 Spain (1967) 6,168 9-2 Sweden (1966) 506 4-1 Yugoslavia (1964) 2,358 59 North America Barbados (1960) 40 5-4 Canada (1968) 3,500 9-7 El Salvador (1967) 1,410 10-2 Jamaica (1960) 826 13-0 Mexico (1968) 12,402 6-1 Panama (1967) 428 8-5 United States (1964) 39,477 9.9 South America Chile (1966) 2,164 8-1 Asia Israel (1963) 614 10-4 Japan (1963) 8,794 5-3 Singapore (1968) 343 7.3 Africa South Africa Asiatic population (1963) 83 5-8 Coloured pop. (1963) 573 7.7 White pop. (1963) 730 9-8 United Arab Republic (1957) 4,460 10-1 Oceania Australia (1967) 2,288 10-1 New Zealand (1968) 666 10-8 Countries where twinning rate Is quoted Irrespective of whether twins are alive or still-born