Dear Tillie, Thanks for your question. Whether or not the twins share the same amniotic sac does not determine if they are identical or fraternal. Identical twins occur when one egg divides into two, resulting in the babies having the same genetic makeup.
Fraternal twins occur when two separate eggs are fertilized.
Your girls could indeed be identical twins, especially if they look a great deal alike. Sharing the same blood type isn't an indication, however, as it's quite common for siblings within any family to have the same blood type. The only way to know for sure is to have them genetically tested. Your pediatrician will be able to help you learn how to do that. Inc. All rights reserved.