# 3 outta 5 eggs have twins! what are the odds? (& should I be afraid?)

Well, I’m not really afraid, but seriously, here’s a picture of what was my breakfast-to-be this morning. What you see (4 yolks if you don’t wanna click) came from 2 cracked eggs, back to back. The other day I cracked open 3 eggs and found a pair of twins.

Thus, if you’re doing the math, of the carton of 10 eggs I’ve so far cracked 5 to find 3 sets of twins! This is unusual, right? I mean, I am broke and too lazy to go to the store in any case so I’m not complaining. (In fact I’m kinda hoping this trend continues). But what are the odds? Would this indicate some variable other than pure chance at play?

If you’re buying jumbo eggs, it’s not terribly unusual. Don’t know what the odds are, though.

I post on a website that has a lot of farmers and other people who keep chickens, and they said that the chances of both chicks surviving in a double-yolked egg are remote. They may hatch, but are usually too weak to make it on their own afterwards.

I do agree that double-yolked eggs are cool. Never seen a triple, but I’m sure it’s happened too.

According to thisthe odds are quite long of you seeing what you saw…

Well, actually that article seems to deflate the amazingness of the event by pointing out how the selection process was likely not random. But ok, since I can’t confirm that it wasn’t random, how would you calculate this? (sad how I actually was pretty good at math at one point in my life).

So each double yolk is 1 in 1000. 3 outta 3 would be 1 in 1000^3. How do I account for the 2 misses?

Completely anecdotal, but the posts in this thread suggest to me it’s not as rare as the Daily Mail article suggests.

This would only work if the probabilities were independent, which they aren’t. Some chickens are more prone to laying double-yolked eggs than others, and most chickens at any given farm will be closely related. If your carton happened to come from a farm with a predisposition to double-yolked eggs, then you’d have an elevated chance on all of them.

A local chicken ranch sells whole cartons of double-yolked eggs at their farm stand, just for fun.

For a minute I thought the OP was about close relatives having twin children 3 outta 5 births and you were a woman wondering whether to get pregnant. In which case be very afraid.

You can account for the two misses by multiplying by C(5,3) = 10, the number of ways of picking 3 eggs out of 5. (This is approximate, but good enough because 1/1000 is very small.) Assuming (counterfactually) that the eggs are independent, that makes the odds about 1 in 100 million.

But you have to adjust for all the days you did not find double yolks. Assuming there were 100 opportunities for this coincidence during the year, the chance is 1 in a million that this would happen to you once this year.

Is one in a million a frightening coincidence? According to John E. Littlewood a person will notice such a coincidence, in one form or another, about once a month.

Well no, I was specifically asking about the odds of finding 3 out of the first 5 eggs used in a single carton of 10. The focus wasn’t on me, or a person in general finding double yolks, but on the carton.

I’m still not sure whether I should think this is really cool or not, but I’m much farther away from thinking it is now than I was at that moment when I looked down and unexpectedly noticed 4 yolks in the bowl.

On Christmas day we had smoked salmon and scrambled eggs for breakfast (a bit of a tradition). I broke eight eggs into a bowl and when I went to beat them I was amazed to see twelve yolks. Naturally everyone had to come and admire them before I beat them.

I used to do a busy weekly barbecue where bacon and egg rolls were a popular choice. Double yolks were a rarity, except once. On that occasion, out of a carton of a dozen eggs, 8 were double yolked.

OK, so what I’m getting from this is that, to find a single double yolk in a carton is actually the more improbable event. Multiple or none, not so much.

(I’m of course being a bit facetious, though it would be interesting if someone could make a case for why I shouldn’t be).

All that extra cholesterol!

But the yolk of an egg isn’t the embryo, is it? Do double-yoked eggs also have two embryos?

Ladies and gentleman, I give you eggs 6 and 7 of the carton.

I am confused. If the story is true, then the odds are 100%.

Of course, you can ask for the likelihood of an event happening retrospectively. When someone is asking about the odds of something happening that has already happened, they’re obviously not talking about whether it actually happened or not, which is self-evident.

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