A general stereotype about identical twins is that they are clones. They act alike, look alike, and are expected to be "identical." However, the term identical twins actually refers to a type of twinning, and describes how they form, not what they look like.
- The causes of monozygotic twinning are generally unknown and unidentified. No one really knows why an egg splits; technically it's a malfunction of the normal development process.
- There's no hereditary trait that influences a predisposition to having identical twins. Identical twins do not run in families. Although there are families with a high incidence of identical twins, it is due to chance, coincidence or plain good luck.
- Identical twins represent about a third of all twins. Dizygotic twins are twice as common as monozygotic.
- Birth rate statistics for identical twinning have remained stable over the years, despite the overall increase in twins and multiples since the late 1980's. The odds of having identical twins is about 3 in 1,000, whereas the birthrate for all twins is about 32.2 in 1,000.
- Identical twinning is not generally influenced by fertility-enhancing treatments like drugs or in vitro, although monozygotic twins have been produced in pregnancies that were the result of such treatments.
- Birth rates for identical twins are consistent across populations; it is the same regardless of race, geography or maternal age.
Despite their shared gene set, identical twins are unique individuals. No two individuals are exactly alike.
No, this is a myth. Even many doctors will mistakenly identify twins as fraternal because there are two placentas. It depends on when the egg splits. If it is early enough, the two embryos will implant separately in the uterus and develop individual placentas. If the split occurs later, they may share a placenta.
Some types of monozygotic twins do experience conditions which put them at risk during pregnancy. Twins who share a placenta may be at risk for Twin-to-Twin Transfusion Syndrome. "Mo-Mo" twins (monochorionic / monoamnionic) are contained in a single amniotic sac, and their umbilical cords may become entangled and compressed.
You can't necessarily tell by looking. Although many identical twins share a physical resemblance, so do many dizygotic (fraternal) twins). Clues to zygosity can be revealed in many ways.
Many people wonder whether fingerprinting can be used to distinguish between two twins who look remarkably alike.
The short answer is no. Identical twins are either two girls or two boys. The longer answer is that there is a very rare exception to this rule that involves a chromosomal defect.
Yes.
Many people believe that identical twins share a special connection, including the ability to read each other's minds.
Twin talk? Or baby babble? Terms such as idioglossia, autonomous language or cryptophasia describe the phenomenon of twin language, a fascinating concept that has intrigued researchers and parents alike.
Every parent should work with their school to determine the optimal classroom placement for their children. It can be a difficult decision.
With a similar genetic background, many identical twins find that they have the same preferences for establishing relationships. They may share many of the same friends. But all twins should be encouraged as individuals, and given opportunities to develop relationships as such.
Every family has to decide this issue based on their individual circumstances.
Distinguishing clothing definitely makes it easier to tell twins apart if they look alike.
It's important for parents of twins to encourage their children's individuality.