Do twins run in the family?
Do twins run in the family?
Yes, some types of twins can run in families, but it depends on the type of twin:
Fraternal twins
Also known as dizygotic twins, fraternal twins are more likely to run in families. If a close relative, like a sibling or parent, has had fraternal twins, you're about twice as likely to have them too. This is because fraternal twins are more likely to occur when more than one egg is released during a menstrual cycle, a condition called hyperovulation. Hyperovulation can be influenced by genetics, but other factors also play a role, such as age, ethnicity, and diet.
Identical twins
Identical twins, also known as monozygotic twins, do not run in families. Anyone has the same chance of having identical twins, which is about 1 in 250. This is because identical twins occur when a single embryo splits spontaneously, which is not linked to genetics.
Other factors that can increase the likelihood of having twins include:
Having previously given birth to twins
Using assisted reproductive technologies like in vitro fertilization (IVF