# What is the statistical probability of a woman having twins by 2 men?
**URL:** https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295
**Category:** Factual Questions
**Created:** [April 7, 2005, 10:15pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295 "2005-04-07T22:15:42Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@Superdude](https://boards.straightdope.com/u/Superdude)
#### Post date: [April 7, 2005, 10:15pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/1 "2005-04-07T22:15:42Z")
Follow me through, here.
I would imagine that it’s - however rare - technically feasible that a woman could have TWO eggs be fertilized on the same day by two different men. I don’t know of any cases where this has actually happened, but it seems that, on some occasion, the fallopian tubes could produce two eggs, that this woman could have sex with two different men in one day, and that those two eggs could be fertilized by the two different partners on that day.
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### Author:  [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)
#### Post date: [April 7, 2005, 10:31pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/2 "2005-04-07T22:31:50Z")
> [@Superdude](#):
>
> Follow me through, here.
>
> I would imagine that it’s - however rare - technically feasible that a woman could have TWO eggs be fertilized on the same day by two different men. I don’t know of any cases where this has actually happened, but it seems that, on some occasion, the fallopian tubes could produce two eggs, that this woman could have sex with two different men in one day, and that those two eggs could be fertilized by the two different partners on that day.
It’s happened, it’s called _Superfecundation_. It’s unlikely. Fraternal twins are uncommon to begin with (1 in 90 in the US), so you have to figure the odds of one woman producing two ova at the same time, then having sex with two fertile men within the right time frame (I won’t hazard a guess here). Then the odds that each guy will fertilize each egg (probably less than 50-50).
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### Author:  [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)
#### Post date: [April 7, 2005, 10:50pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/3 "2005-04-07T22:50:35Z")
I’ve heard it happens a lot with cats.
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### Author:  [@MikeS](https://boards.straightdope.com/u/MikeS)
#### Post date: [April 7, 2005, 11:30pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/4 "2005-04-07T23:30:43Z")
[Cecil](http://www.straightdope.com/classics/a2_213.html) on superfecundation.
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### Author:  [@scm1001](https://boards.straightdope.com/u/scm1001)
#### Post date: [April 8, 2005, 9:51am UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/5 "2005-04-08T09:51:10Z")
it was estimated that about 1/400 twins may be from different fathers
from [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list\_uids=7871943&dopt=Abstract](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7871943&dopt=Abstract)
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### Author:  [@anson2995](https://boards.straightdope.com/u/anson2995)
#### Post date: [April 8, 2005, 1:58pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/6 "2005-04-08T13:58:49Z")
> [@Qadgop the Mercotan](#):
>
> Fraternal twins are uncommon to begin with (1 in 90 in the US)
Does that mean 1 in 90 sets of twins? I’m the father of fraternal twins (one boy one girl), and I’m surprised to see it’s that unusual.
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### Author:  [@Acsenray](https://boards.straightdope.com/u/Acsenray)
#### Post date: [April 8, 2005, 3:13pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/7 "2005-04-08T15:13:24Z")
I have a pair of friends who look exactly the same in every way, but who claim that they are fraternal, not identical, twins. Is that possible?
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### Author:  [@wasson](https://boards.straightdope.com/u/wasson)
#### Post date: [April 8, 2005, 3:48pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/8 "2005-04-08T15:48:17Z")
> [@acsenray](#):
>
> I have a pair of friends who look exactly the same in every way, but who claim that they are fraternal, not identical, twins. Is that possible?
Sure. Apparently, the Olsen twins are actually fraternal. Go figure.
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### Author:  [@chrisk](https://boards.straightdope.com/u/chrisk)
#### Post date: [April 8, 2005, 3:59pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/9 "2005-04-08T15:59:09Z")
> [@anson2995](#):
>
> Does that mean 1 in 90 sets of twins? I’m the father of fraternal twins (one boy one girl), and I’m surprised to see it’s that unusual.
No, I think it’s meant that 1 in 90 humans born in the US is a fraternal twin.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [April 8, 2005, 9:25pm UTC](https://boards.straightdope.com/t/what-is-the-statistical-probability-of-a-woman-having-twins-by-2-men/298295/10 "2005-04-08T21:25:27Z")
Or that one in 90 pregnancies is fraternal twins, which is significantly different from 1 in 90 persons.