Fraternal twins: Learn the key differences

Learn the key differences and similarities between fraternal and identical twins, such as genetic code, gender, blood type, appearance, and risks. Find out how to identify and test for zygosity, and how environmental factors can affect twin phenotypes. Fraternal twins (also called dizygotic twins) result from the fertilization of two separate eggs with two different sperm during the same pregnancy. Fraternal twins may not have the same sex or appearance. They share half their genomes, just like any other siblings. Fraternal twins are like a pair of siblings who happen to grow together in their mom’s belly at the same time. But here’s the twist: instead of one egg splitting into two, two separate eggs are fertilized by two different sperms. This means they’re like two separate pregnancies happening together! Fraternal Twins: Varieties, Genetics, and Parenting Now, identical twins are like a copy-paste situation. One egg gets fertilized, and then it splits into two, making two babies that share ... Fraternal twins are twins who develop from 2 separate eggs and have different genes. Learn how to tell the difference between fraternal and identical twins, and why it matters for pregnancy and health.