I have over heard several times when someone would say they are going to have twins because twins run in their family. My mum comes from a family where every one of her sisters have twins, but she did not and so she is hoping that one of her kids would have twins.
This has made me question the thought that the probability of one having twins increases because they have a family member that had twins.
Genetics can definitely play a role in having fraternal twins. Fraternal twins are children that are born on the same day from one mother but don't look alike. For example, a woman that has a sibling that is a fraternal twin is more likely to have twins. Having identical twins is not genetic. On the other hand, fraternal twins can run in families.
However, for a given pregnancy, only the mother’s genetics matter. Hyper-ovulation occurs when a woman’s ovaries release more than one egg during each cycle. A woman that experiences hyper-ovulation has a high possibility of having twins.
Fraternal twins happen when two eggs are simultaneously fertilized instead of just one. A father’s genes can’t make a woman release two eggs. This means that if you have an history of having twins in your family, only your daughter can carry the gene not your son. This because a father’s genes can’t make the woman release two eggs at the same time.
However if the history of having twins is in a man’s family there is a possibility that he would pass the gene onto his daughter. So that means that his daughter then has an higher possibility of having twins.
Women who use fertility drugs are also likely to have multiple birth because fertility drugs stimulate your ovaries, increasing the odds that you'll release several eggs at the same time. Women age 35 or older also have a higher chance of having fraternal twins or higher order multiples.