Self Assessment Answer # 5 for Lesson 5 by Dr Jamie Love 2002 - 2005

The new child will not be identical to the twins. This new child would have developed from a new zygote and that zygote would have been made by the fusion of a new sperm and a new egg. The chance that both those gametes are identical to the ones that created the zygote-twins is (effectively) impossible! The crossing over in prophase I and the random segregation at anaphase I that occurred in the parents - in order to make the haploid cells for gametes - produce millions (perhaps billions) of different possibilities. This is why brother or sisters in a family are not identical unless they are identical twins.

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