# Identical quadruplets?

**URL:** <https://boards.straightdope.com/t/identical-quadruplets/750454>\
**Category:** Factual Questions\
**Created:** [March 28, 2016, 12:29pm UTC](https://boards.straightdope.com/t/identical-quadruplets/750454 "2016-03-28T12:29:46Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\
**Post date:** [March 28, 2016, 12:29pm UTC](https://boards.straightdope.com/t/identical-quadruplets/750454/1 "2016-03-28T12:29:46Z")

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My question actually applies to identical multiple births of any number, but was stimulated by the recent news of a mother being pregnant with identical quadruplets, and how unlikely that is.

Give that the babies have not been born yet, how is it determined that they are **identical** quadruplets rather than fraternal quadruplets? Even the fact that they are all the same gender would not necessarily imply that they are identical. 😕

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**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\
**Post date:** [March 28, 2016, 1:21pm UTC](https://boards.straightdope.com/t/identical-quadruplets/750454/2 "2016-03-28T13:21:31Z")

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They either have cell samples from all 4, or they have some other evidence that the fetus started as a single cell and later split. Dunno what that evidence might be.

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**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\
**Post date:** [March 28, 2016, 1:25pm UTC](https://boards.straightdope.com/t/identical-quadruplets/750454/3 "2016-03-28T13:25:49Z")

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Monozygotic (identical) multiple births frequently share the same placenta and might even have a single amniotic sac. Fraternal multiples _always_ have separate placentas and amniotic sacs.

So, if on ultrasound you have four babies all sharing a single placenta you have identical quads.

That’s what comes to mind first, there may be other ways to know I’m not familar with.

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**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\
**Post date:** [March 28, 2016, 1:30pm UTC](https://boards.straightdope.com/t/identical-quadruplets/750454/4 "2016-03-28T13:30:18Z")

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> [@Broomstick](#):
>
> Monozygotic (identical) multiple births frequently share the same placenta and might even have a single amniotic sac. Fraternal multiples _always_ have separate placentas and amniotic sacs.
> 
> So, if on ultrasound you have four babies all sharing a single placenta you have identical quads.
> 
> That’s what comes to mind first, there may be other ways to know I’m not familar with.

OK - Thanks!