Happy #BumpDay! If you have a family full of twins, you may have asked yourself if your chances of having twins increases. The answer is complicated, but can be broken down what kind of twins they are and which side of the family has twins.

Having identical twins does not run in families, but genetics can play a role in having fraternal twins. If there are fraternal twins on the mother’s side of the family, the chances of her also conceiving fraternal twins can double.

This is because women can pass down a gene that can cause “hyperovulation,” or when a woman releases more than one egg during each menstrual cycle. Fraternal twins happen when two babies from two eggs release from the ovaries simultaneously.

On the other hand, having fraternal twins on the father’s side will not increase the chances of having fraternal twins. The theory that twins skip a generation is actually based on this occurrence. If a man inherits the hyperovulation gene from his mother, it will have no effect on his likelihood to have twins. But, he may pass this gene onto his daughter: effectively “skipping” a generation.

If there are identical twins in your family, this is a spontaneous occurrence and won’t increase your odds of having identical twins.

The chance of having twins is only about 3.5 percent, but there are some other factors that can increase your chances.

These are some other factors that make you more likely to have twins:

  • 35 or older
  • Taller than average height
  • Overweight
  • Taking fertility treatments
  • On a second (or higher) pregnancy