Twin Influence

Name: Ruby
Status: educator
Grade: other
Location: N/A

Question: My husband has had twins running in his family. Is it more
likely for twins to come from the mother's or father's side of the
family?
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With regard to fraternal twins, since these twins are the result of 
multiple ovulation, these is no way this could be influenced by the 
biological father or his relatives.
 
Ron Baker, Ph.D.

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There are two kinds of twins, identical and fraternal. There is no known
genetic / heredity cause of identical twins. So if a family has multiple
instances of identical twins, it's just chance.

As for fraternal twins, the probability may be influenced by heredity, but
it's not gender-specific. I have read in non-scientific literature that
there is a gene for hyper-ovulation, found on the X chromosome.
Hyperovulation means releasing more than one egg during ovulation, which can
result in fraternal twins. I have not verified this in scientific
literature, and the topic is outside my field of expertise. Both males and
females can have this gene, as both males and females have an X chromosome.
Of course, only females ovulate, so males carry the gene, but do not express
it. The probability of having twins is higher in mothers with the gene, but
she can get that gene from either her father or her mother. The odds are not
gender-influenced, though. If the mother's family has more instances of
fraternal twins, then perhaps they carry a gene for hyperovulation, and
perhaps the mother carries that gene as well. The same is true for the
father.

In your case, your husband having multiple instances of twins in his family
will not cause you to be more likely to have twins. Your genes came from
your family, and having twins is determined by you, not by him (his sperm
would fertilize whichever eggs you ovulate -- whether it's one or more than
one).

Hope this helps,
Burr
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