Is the tendency to have twins inherrited?

Yes, the tendency to have twins is inherited. Twin studies have shown that the concordance rate for monozygotic (identical) twins is much higher than that for dizygotic (fraternal) twins. This suggests that there is a genetic component to twinning.

Specifically, twinning is thought to be influenced by a number of genes, including those involved in the development of the ovaries, fallopian tubes, and uterus. For example, some genes may affect the number of eggs that are released during ovulation, while others may affect the ability of the eggs to implant in the uterus. Additionally, environmental factors such as maternal age, diet, and stress may also play a role in twinning.

The exact genetic mechanisms that contribute to twinning are not yet fully understood. However, twin studies have provided valuable insights into the role of genes in this process.