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Zygosity refers to the genetic makeup of the pregnancy, or the number of zygotes that become fertilized leading to a multiple birth. Twins, in rarer cases triplets, quadruplets (four), quintuplets (five), arising from a single fertilized ovum are termed monozygotic (MZ).
Monozygotic twins reared apart (MZA) allow direct estimates of genetic effects on behavior and health, because they share all their genes, but differ in their environments. Dizygotic twins reared apart (DZA) differ in their environments, but share only half their genes, on average.
The processes that give rise to monozygotic (MZ) twins remain elusive. This article describes various theories of MZ twinning that have been examined over the years, although they continue to be speculative.
1 sty 2020 · A closer look at the frequencies of the East Flanders Prospective Twin Survey (Derom and Derom, 2005), where genetic assessment of zygosity is nearly 100%, reveals that 44% of spontaneous twins are monozygotic, compared to 16% of spontaneous triplets. However, when one counts the number of zygotes that underwent splitting, one should also count ...
Biology and Genetics of Dizygotic and Monozygotic Twinning. Jeffrey J. Beck, Susanne Bruins, Hamdi Mbarek, Gareth E. Davies, and Dorret I. Boomsma. Contents 3.1 Introduction – 33 3.2 Zygosity, Chorionicity, Placentation of Twinning – 34 3.3 Zygosity Determination – 36.
1 lis 1990 · Since 1979, a continuing study of monozygotic and dizygotic twins, separated in infancy and reared apart, has subjected more than 100 sets of reared-apart twins or triplets to a week of...
Since 1979, a continuing study of monozygotic and dizygotic twins, separated in infancy and reared apart, has subjected more than 100 sets of reared-apart twins or triplets to a week of intensive psychological and physio- logical assessment.
