Nonidentical twins occur when a woman produces two separate eggs that are then fertilized by two different sperm cells. The resulting twins sometimes look alike, but have separate genetic identities, like children of the same parents born during different pregnancies. Another name for nonidentical twins is fraternal twins.Continue Reading
Nonidentical twins only form when two eggs release during the same ovulation. In some cases, the eggs release simultaneously. In others, the ovaries initially release one egg. After fertilization that egg begins moving to the uterus to attach. The ovaries then release a second egg, fertilized by a later act of sexual intercourse. This leads to the potential of a woman giving birth to nonidentical twins with two separate fathers. In this case, the genetic identity of the twins is the same as a half-sibling born from separate pregnancies.
The sex of fraternal twins has a chance of differing. Identical twins develop when a single egg fertilized by a single sperm splits to form two different babies. These twins have the same genetic identity. Identical twins are always the same sex.
While some women produce multiple eggs with every ovulation, others begin producing multiple eggs as they grow older. Genetics also plays a role in the chance of conceiving twins. Use of fertility drugs increases the chance of producing more than one egg during each cycle.Learn more about Biology
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Artificial embryo twinning is a method of making clones that mimics the natural process of creating identical twins, according to the Genetic Science Learning Center. It uses the same approach as natural cloning, but it is performed in a Petri dish rather than inside the mother.Full Answer >
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Paternal and maternal twins, commonly known as fraternal and identical twins, are distinguished by the different ways the multiple pregnancy begins. Identical twins begin as a single zygote that splits into two or more developing embryos. Fraternal twins are usually the result of multiple eggs being present for fertilization.Full Answer >