There have only been two reported cases of semiidentical twins, so this type is extremely rare In semiidentical twins, two separate sperm fertilize one egg The fertilized egg then splits in twoAnswer (1 of 6) In 999% of cases boy/girl twins are nonidentical However, in some extremely rare cases resulting from a genetic mutation, identical twins from an egg and sperm which began as male (XY) can develop into a male / female pair This Marilyn responds You are (We're assuming fraternal twins Identical twins are always the same sex) These are the possibilities 1) Baby
Rare Semi Identical Twins Born To Australian Mum From Two Different Sperm
