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The human twin birth rate in the United States rose 76% from 1980 through 2009, from 9.4 to 16.7 twin sets (18.8 to 33.3 twins) per 1,000 births. [5] The Yoruba people have the highest rate of twinning in the world, at 45–50 twin sets (90–100 twins) per 1,000 live births, [6] [7] [8] possibly because of high consumption of a specific type of yam containing a natural phytoestrogen which may ...
Monozygotic twins result from the fertilization of one egg and the division of that single embryo forming two embryos. [4] However, just because a set of twins share the same genetic information, it does not mean they will exhibit the same traits and behaviors. There are different versions of a gene, which are called alleles. How a gene is ...
The power of twin designs arises from the fact that twins may be either identical (monozygotic (MZ), i.e. developing from a single fertilized egg and therefore sharing all of their polymorphic alleles) or fraternal (dizygotic (DZ), i.e. developing from two fertilized eggs and therefore sharing on average 50% of their alleles, the same level of genetic similarity found in non-twin siblings).
Quaternary twins occur when one set of identical twins has children with another set of identical twins. “They share DNA in the same way siblings share DNA,” Dr. John Pappas, ...
This rare occurrence, when twins have the same mother but different fathers, is called superfecundation. This case is thought to be the first set of bi-paternal twins born in Vietnam, though there ...
Identical or monozygotic twins share their genes, while fraternal or dizygotic twins are only as genetically similar as any other sibling pair. When twins both share a trait, they are concordant for this trait; and when they differ they are discordant. If identical twins have a higher rate of concordance for a trait than fraternal twins, it ...
Image credits: MontEcola #5. My wife is an identical twin. When we first started dating I could tell them apart from their voices, smell, makeup, and eyes.
A DNA segment is identical by descent (IBD) in two or more individuals if: they have inherited it from a common ancestor without recombination, that is, the segment has the same ancestral origin in these individuals; the segment is maximal, that is, it is delimited at both ends by ancestral recombination events. [1]