Thursday, November 17, 2011

Forum Thread: Fraternal/Sororal (Dizygotic) Twins

Do you have any comments or stories about the fraternal twins in your life? If so please post in the comment section below.

Please note that your comment may be used as a stand-alone post and by posting a comment, you are granting the webmaster permission to use your content for this blog.

If you would rather email your story, need more info, and/or have an idea for a forum thread, contact the webmaster.

Definition of "Fraternal Twin" from Wikipedia:
Fraternal or dizygotic (DZ) twins (also referred to as "non-identical twins," "dissimilar twins," "biovular twins," and, in cases of females, sororal twins) usually occur when two fertilized egg are implanted in the uterus wall at the same time. When two eggs are independently fertilized by two different sperm cells, fraternal twins result. The two eggs, or ova, form two zygotes; hence, the terms dizygotic and biovular.

Dizygotic twins, like any other siblings, have an extremely small chance of having the same chromosome profile. Like any other siblings, dizygotic twins may look similar, particularly given that they are the same age. However, dizygotic twins may also look very different from each other. They may be of different sexes or the same sex. The same holds true for brothers and sisters from the same parents, meaning that fraternal and/or sororal twins are simply siblings who happen to be the same age.

Studies show that there is a genetic basis for dizygotic twinning. However, it is only their mother that has any effect on the chances of having such twins; there is no known mechanism for a father to cause the release of more than one ovum.

Dizygotic twinning ranges from six per thousand births in Japan (similar to the rate of monozygotic twins) to 14 and more per thousand in some African countries.

Dizygotic twins are also more common for older mothers, with twinning rates doubling in mothers over the age of 35. With the advent of technologies and techniques to assist women in getting pregnant, the rate of fraternals has increased markedly.

No comments:

Post a Comment

Your on-topic comments are welcome!

The following types of comments will be deleted from this thread:

--Comments with outside links
--Off topic comments
--Advertising and general spam
--Hate speech
--Name calling
--Bad language

Forum Threads