This means there is a higher chance that two eggs could get fertilized at once, leading to fraternal twins. The gene versions that increase the chance of hyperovulation can be passed down from parent to child.
http://genetics.thetech.org/ask-a-geneticist/twin-genetics
Women carrying more than one baby are at higher risk of: 1  Preterm birth. 2  Low birth weight. 3  Preeclampsia. 4  Gestational diabetes. 5  Cesarean birth.
https://www.womenshealth.gov/pregnancy/youre-pregnant-now-what/twins-triplets-and-other-multiples
-A curious adult June 25, 2014 That is a very interesting question! And one that many people wonder about. In fact, we answered a very similar question many years ago. Twin genetics depend on what kind of twins we are talking about. Having identical twins is not genetic. On the other hand, fraternal twins can run in families. Genetics can definitely play a role in having fraternal twins. For example, a woman that has a sibling that is a fraternal twin is 2.5 times more likely to have twins than average!
http://genetics.thetech.org/ask-a-geneticist/twin-genetics
Studies with twins have been quite interesting. 1  If we make a list of characteristic traits, we find that they vary in how much they owe to heredity. For example: 2  Eye colour: entirely inherited. 3  Weight, height: partly inherited, partly environmental. 4  Which language you speak: entirely environmental.
https://simple.wikipedia.org/wiki/Identical_twins
Identical twins. Identical twins start out as genetically identical: they have the same alleles. They are formed by a fertilised egg dividing into two separate individuals. They are always of the same sex, and are monozygotic or MZ twins (mono = one; zygote = fertilised egg).
https://simple.wikipedia.org/wiki/Identical_twins
Twins, triplets, and other multiples If you are pregnant with more than one baby, you are far from alone. In the past two decades, the number of multiple births has climbed way up in the United States.
https://www.womenshealth.gov/pregnancy/youre-pregnant-now-what/twins-triplets-and-other-multiples
The important difference between identical and fraternal twins is the number of fertilized eggs involved. Identical twins come from a single fertilized egg. Fraternal twins come from two different ones. Identical twins happen when a single embryo splits in two soon after fertilization. This is why identical twins have identical DNA.
http://genetics.thetech.org/ask-a-geneticist/twin-genetics
This is why the DNA of fraternal twins is different. In fact, fhe DNA of fraternal twins is no more similar than the DNA any other sibling pair. Usually, a woman only releases a single egg at a time. Fraternal twins can only happen if a mother releases two eggs in one cycle. This is called hyperovulation. Unlike embryo splitting, ovulation is a normal biological process that is controlled by our genes.
http://genetics.thetech.org/ask-a-geneticist/twin-genetics
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http://genetics.thetech.org/ask-a-geneticist/twin-genetics
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. It sounds like fraternal twins do indeed run in your family! But, since your son is the father, his genes are on the wrong side of the family tree. So, your family history likely didn’t play a role in his wife’s twin pregnancy.
http://genetics.thetech.org/ask-a-geneticist/twin-genetics
how does identical twins get created
Identical twins happen when a single embryo splits in two soon after fertilization.