Developmental and Fetal Origins of Differences in Monozygotic Twins: From Genetics to Environmental Factors examines the major causes of discordance in monozygotic twins, from genetic, to environmental influences, including discussions on the genetic, epigenetic, fetal and environmental factors. Twin differences discussed include malformations, deformations and disruptions secondary to inequitable division of the early embryo, chromosome and single gene mosaicism, Nonrandom X chromosome inactivation, mitochondrial heteroplasmy, epigenetic variation, and variable and inequitable blood supply, among other influences. Differences in hemoglobin levels, placentation and amniotic fluid are also examined, while full color images illustrate discordant anomalies and twin differences throughout.