Twins [13+]

Tags:: Twins Identical Twins Non-identical Babies

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By: periskianis
Subscribers: 6
Updated: 18-Nov-09
Videos: 32

International
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Views: 1,328
Added: 31-May-09

Twins can occur in two ways. In around a third of cases just one egg is fertilised but within days it splits, each half developing into an identical baby. In the remaining two-thirds, two eggs are released at the same time and both fertilised by separate sperm resulting in two non-identical babies.

Non-identical twins (also called fraternal, dizygotic, DZ or binovular) are no more alike than any other brothers or sisters. These twins are conceived at the same time or one following the other in a single menstrual cycle - so non-identical twins can even have different fathers. Non-identical twins share, on average, just half their genes, so they can look very like each other or totally different - most obvious when mixed race parents have white and black twins.