Twin types : more than just two -- Living laboratories : double designs and multiple methods -- Mythconceptions about twin conceptions I -- Mythconceptions about twin conceptions II -- Identical or fraternal? telling twins apart -- Biological complexities, myths, and realities -- Mind readers? twin telepathy, intelligence, and elite performance -- Going to school and speaking out loud -- Human behavioral variations : sex and sex differences -- Good twin-evil twin and other family ties -- Twins, clones, and other extraordinary pairs -- Twin spouses and unrelated look-alikes : new views -- Of two minds : old questions and fresh answers -- Appendix 1 : What about Hellin's law? and does Weinberg rule? -- Appendix 2 : Right-handed or left-handed? -- Appendix 3 : Polar body twins : a primer -- Appendix 4 : Nancy L. Segal's ten classic books on twins -- Appendix 5 : Glossary of terms and abbreviations.