On Mon, Apr 02, 2007 at 03:32:40PM -0500, Janice McDonald wrote: > fused together in some way, and half-twins or polar body twins, which > are made when an unfertilized ovum splits into two complete, identical > parts and is then fertilized by two different sperm. The frequency of > identical twins is 3.5 per 100 births (1) and the frequency of > conjoined twins is 1 birth per 50,000 with only 100 known cases > surviving their first year (5). > see? you cant argue with her. janice
they'd still share more than half their genetic background, though, unless they did have two different fathers. and given the rarity of that, i doubt any of the 100 cases that survived their first year were of that tiny population as well. i'm amazed, janice, that you'll give judy credit for serious medical anomalies, but not credit me for my very own pony. --vicka
