Though much has been written about twins, very little research has been done into their everyday lives, both postnatal and prenatal. In this fascinating new study Alessandra Piontelli follows the development and behaviour of thirty pairs of twins from their early life in the womb through to their third year of childhood. Drawing on detailed ultrasound observations and work with mothers and families in clinical and natural settings, the text traces the subtle ways in which various types of twins live, behave and interact with their unequally shared and unique pre- and postnatal environments. Piontelli shows how from early on distinctive and personal traits can be seen in the behaviour of each member of a twin couple and how these traits continue and strengthen well beyond birth. The book describes not only the behaviour of the twins, but the impact they have on the lives of their family and carers - what family members say, how they react and how the family changes. Scientifically based, but warmly human in content, this unique longitudinal study offers new insight for professionals working with mothers and families of twins and for researchers in human development across a range of disciplines.