The term “identical twins” is generally used as a synonym for “monozygotic (MZ) twins.” Both terms assume that that the twins developed from the same fertilized egg (zygote), have identical DNA, and therefore look identical. But, as explained here, identical twins do not always look exactly the same. And male/female twins certainly don’t look identical! […]
No! In about 21% of identical (monozygotic or MZ) twin pairs, one twin is right-handed and the other is either left-handed or ambidextrous. Since identical twins share identical genes, this is evidence that handedness is not a totally genetic trait. Left-handedness is more likely to occur in twins than in single individuals. Only about 10% […]
If your twin develops certain diseases, you may have an increased risk of developing that disease. This risk may be higher if you are identical twins than if you are fraternal twins. If you would like additional information about how your twin’s health might impact your own health, contact your health care provider or a […]
Study objectives: Mitochondrial DNA (mtDNA) copy number is an important component of mitochondrial function and varies with age, disease, and environmental factors. We aimed to determine whether mtDNA copy number varies with habitual differences in sleep duration within pairs of monozygotic twins. Setting: Academic clinical research center. Participants: 15 sleep duration discordant monozygotic twin pairs (30 twins, 80% […]
Half-identical twins are also called polar body twins. At the end of the normal process of ovulation, the developing egg divides into two cells. Each cell has the same number of chromosomes in the nucleus, but different amounts of cytoplasm. The bigger cell (with most of the cytoplasm) is the egg, and the much smaller […]
