How+are+twins+born?


 * __HOW ARE TWINS BORN?__**

Answer the question below, append new answers to the top of this page. _ __Response 1:__ There are two types of twins: there are a single egg twins and there are a double egg twins. The single egg twins are made because one egg has two sperms in it so the embryo splits creating two identical twins. They are very similar (look like each other). They are also called "true" twins. The double egg twins are made when two eggs are each fertilized by one sperm creating two non identical twins. They don't always look similar and can be of the different gender.
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Sources: 1. Encyclopedia for the youngest, Nasa Djeca, Zagreb, Croatia

By Phillip Aubrecht

__Additional Responses:__

There are two types of twins; Identical twins and fraternal twins. Identical twins are born when the sperm fertilizes one egg, and it splits into two, and are each placed in two different embryos. Because the embryos are the same, with the same eggs in them, the twins share the same organs, the same sex, as well as the same DNA. The correct term for identical twins is Monozygotic; Single (being mono) and fertilized eggs (meaning zoygote). Dizygotic twins (more commonly called fraternal twins) are the result of two different eggs that were fertilized by two different sperm. Fraternal twins are commonly a different sex, they share about 50% of each others genetic traits as well as being born at totally different times. Most of the time, women only release one egg, so fraternal twins are more rare then identical twins.

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Taylor Fraser February 14, 2012

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