Definitions by Geoff Doe

Identical twins

Identical twins, also known as monozygotic twins, develop from a single fertilized egg that splits into two embryos. This means they share the exact same genetic material, making them look remarkably similar, often down to fine anatomical and biochemical details. They are always the same sex. While their genetic makeup is identical, environmental factors can still influence their development, leading to subtle differences in appearance.

Tom and Josh, who are identical twins, have the same eye color.

Identical twins by Geoff Doe October 19, 2026