For families, twins bring a unique experience—two children arriving at once, often sharing milestones, bonds, and experiences in ways that are truly special. From a biological perspective, however, twin pregnancies involve a complex interplay of genetics, hormones, and environmental factors.
When this occurs later in life, especially in a woman’s late 50s, it becomes even more remarkable.
How Twin Pregnancies Occur
Twin pregnancies generally fall into two main categories:
Fraternal (dizygotic) twins: Occur when two separate eggs are fertilized by two different sperm.
Identical (monozygotic) twins: Occur when a single fertilized egg splits into two embryos.
Fraternal twins are more common and are often influenced by genetics and hormonal factors. Identical twins, on the other hand, occur randomly and are not typically linked to heredity.
Understanding what increases the chances of either type helps explain why some pregnancies result in multiples.
The Role of Genetics in Twin Births
One of the strongest natural influences on twin pregnancies is family history—especially on the mother’s side.
