Of Geminates and Gemellology

Twins have always attracted attentionÐ Romulus and Remus, Castor and Pollux, Jacob and Esau, Fafner and Fasold; there has always been intrigue, mystery and confusion surrounding two-in-one and one-in-two. The interest for Laterality and lateralisation is compounded, because if it is the difference between an individual ’ s two sides that results in laterality, how are those two sides represented in twins, particularly monozygotic twins that once were one? This Special Issue of Laterality clearly indicates a continuing interest in the relationship of twinning and laterality, and it is a particular pleasure to include both biological and neuropsychological papers. The editors ’ job has been particularly easy since all but one of the papers were submitted spontaneously, and the only editorial tasks were the pleasant ones of putting them together, and writing a light-hearted introduction to accompany the heavier but extremely interesting scientific fare that follows. Finally, although I ’ ve long been interested in twins professionally (McManus, 1980) , I now have two more reasons for fascination. The ultrasound scan below, at fourteen weeks of gestation, shows the first glimpse of our daughters Franziska and Anna, born on June 25th 1999 just as the journal went to press. This Special Issue is dedicated to them and to Christine