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Name: Francine
Status: Student
Age: 16
Location: N/A
Country: N/A
Date: 2001

How do eggs split to form conjoined twins?

Dear Francine,

Here is the simple explanation:

For more detail on twin development, please see this excellent web page from the Univ. of Minn.: um2000/Twins/twins.html

Thanks for the good question,

Jeff Buzby, Ph.D.

I think your question is somewhat incorrect...conjoined twins often develop from a single egg which has incompletely separated, which if it had separated would have produced a set of identical twins. Two eggs ovulated at the same time and fertilized at the same period of a woman's cycle would give non-identical, fraternal twins;.

Peter Faletra Ph.D.
Assistant Director
Science Education
Office of Science
Department of Energy

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