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identical twin not only has to worry about her own cord, but also that of her sister. The twins have a greater risk of TTTS (Twin to Twin Transfusion Syndrome) where placenta is unevenly shared - thus, one gets too much blood and other gets too little.Mirror Twin - Some 25% of identical twins are mirror twins. They have mirror image finger prints, one is left-handed and other is right-handed, and their hair spirals in opposite directions.
Conjoined Twin - Commonly called Siamese twins, they are monoamniotic monochrionic twins who never completely separate. Thus, when they are born they share some part of their body. Often their hips or shoulders, and more rarely their heads, are connected. The majority of conjoined twins are mirror twins. Several successful surgical separations have been performed, allowing twins to live normal lives.
Fraternal Twin - Far more common are fraternal twins, who come from two different eggs fertilized by two different sperm cells. They share 50% of their DNA just as other siblings born at different times do.
Twins of Two - When two separate eggs are fertilized by two different men, twins of two are conceived. The children are genetically half-siblings and share just 25% of their DNA.
One hundred years ago, average parents of twins would have had to guess whether they were identical or fraternal. Nowadays, in addition to sophisticated medical equipment available, parents can have DNA tests done to determine what type of twins their children are.
Nick Smith is an internet marketer specializing in ranking automation. For information about DNA testing for your identical twin, visit Genetree.com.