A twin is one of two offspring produced in the same pregnancy. Twins can either be monozygotic ("identical"), meaning that they develop from one zygote that splits and forms two embryos, or dizygotic ("fraternal") because they develop from two separate eggs that are fertilized by two separate sperm.
From 1980 to 2009, according to a recent report by the National Center for Health Statistics, the rate of twin births rose 76 percent.
Every summer, on the first weekend in August, thousands of twins converge on Twinsburg, Ohio, a small town southeast of Cleveland named by identical twin brothers nearly two centuries ago.
By comparing the likelihood that identical twins share a given trait with the likelihood that fraternal twins share the same trait, researchers can calculate how much of the difference is due to genetic variation. A person's height, for example, is often estimated at 0.8, meaning that 80 percent of the differences in height among individuals in a specific population are due to differences in their genetic makeups.
If a woman inherits a certain gene that causes her to hyper-ovulate (meaning she’s more likely to release multiple eggs during ovulation), her chance of having fraternal twins — which are produced from two separate eggs — increases.
204 — that’s the combined age of Ena Pugh and Lily Millward, a pair of British twins who both celebrated their 102nd birthdays on Jan. 4. And the duo had a whole lot to rejoice: The milestone landed them in the Guinness Book of World Records for being the oldest twins on the planet.
Twinless Twins Support Group, International (TTSGI) exists to provide a safe and compassionate community for twinless twins to experience healing and understanding. We provide support for twins and other multiples who have lost their twin due to death or estrangement at any age.
Identical twins result from a single fertilized egg dividing into separate halves and continuing to develop into two separate but identical babies. These twins are genetically identical, with the same chromosomes and similar physical characteristics. They're the same sex and have the same blood type, hair, and eye color.
Fraternal twins come from two eggs that are fertilized by two separate sperm and are no more alike than other siblings born to the same parents. They may or may not be the same sex. This type of twins is much more common, and only this type is affected by heredity, maternal age, race, and number of prior pregnancies.
A 2004 survey among members of the American College of Obstetricians and Gynecologists found that 81 percent of doctors thought that twins who gestate with separate placentas are fraternal. In fact, 25 to 30 percent of identical twins have separate placentas and amniotic sacs.
Ideoglossia is the term used for the secret language of twins. This secret language actually does not exist. Once twins, as in any other baby, learn to talk, they mispronounce words but because their other half is capable of recognizing and understanding those words, it seems as if they have their own language.
Conjoined twins occur once in every 50,000 to 60,000 births. Most are stillborn.
Approximately 75 percent of conjoined twins are joined at least partially in the chest and share organs with one another. If they have separate sets of organs, chances for surgery and survival are greater than if they share the same organs.