Understanding Digenesis: Types, Causes, and Likelihood

Digenesis (from the Greek words "di" meaning two and "genesis" meaning origin) refers to the process of the formation of two or more embryos from a single fertilized egg. This can occur in various ways, such as:

1. Fraternal twins: When a single fertilized egg splits into two or more embryos, each containing the same genetic material, resulting in siblings who share the same parents but have different birth dates and may look slightly different.
2. Identical twins: When a single fertilized egg splits into two or more embryos, each containing the same genetic material, resulting in siblings who share the same genetic makeup, birth date, and physical characteristics.
3. Chimeric twins: When a single fertilized egg splits into two or more embryos, but one embryo absorbs the other(s), resulting in only one visible twin, while the absorbed twin may remain present as a cluster of cells or tissues within the body.
4. Mixed-type twins: When a single fertilized egg splits into two or more embryos, resulting in a combination of fraternal and identical twins.

Digenesis can occur spontaneously or as a result of medical intervention, such as assisted reproductive technology (ART) like in vitro fertilization (IVF). The likelihood of digenesis depends on various factors, including the mother's age, the number of embryos transferred during ART, and the quality of the embryos.