Find out everything you've always wanted to know about identical twins – from how they form to what makes them unique.

The mature egg can then be fertilized by a sperm cell, which creates a zygote — a fertilized egg cell. After fertilization, the zygote needs to successfully implant into the uterine lining ...

It makes sense that identical twins would have the exact same DNA, right? Spoiler alert: Not always! Here's why. Identical ...

The debate over when human life begins took a sharp turn in Texas, where a state legislator filed a bill that would define an ...

Eggs get fertilized, and by that I mean sperm get ... to form a single cell called a zygote. This highly specialized, totipotent cell marked the beginning of each of us as a unique individual.” ...

Identical twins arise from a single fertilized egg, or zygote, splitting into embryos with duplicate DNA, but what causes the split remains unknown. Zygote splitting was once thought ...