There was a very long comments-discussion on an answer of Can you develop an immunity to chopping onions causing tears?, which triggered an automatic flag. I will delete the discussion from there, but the topic is interesting, so I would suggest that we continue the discussion here.

Content of the comments:

Eyes certainly do change as you age; it's plausible that something happens that's not specific to onions but still helps. – Jefromi♦ ↵ 19 hours ago

@jefromi Well, basic research indicates it is a reflex. I think anything deeper, and this is a medical or bio question, and no longer a culinary one. – SAJ14SAJ ↵ 19 hours ago

@Jefromi Can I ever attest to that! I'm blind as a bat, when the hell did this happen? – Jolenealaska ↵ 18 hours ago

@SAJ14SAJ I think we're quite happy to have biological/medical questions with culinary relevance here, just as we take plenty of chemistry ones. – Jefromi♦ ↵ 18 hours ago

@Jefromi Which is why I answered instead of voting to close as off topic.... but at some point, if we are going to investigate every chemical pathway and effect of the aging process, the culinary depth of the question will have been well exceeded. – SAJ14SAJ ↵ 18 hours ago

Here is a fun fact: syn-Propanethial S-oxide was the chemical of the week of the ACS: acs.org/content/acs/en/molecule-of-the-week/archive/… Who knew it was a celebrity! – SAJ14SAJ ↵ 18 hours ago

If the question's worth answering, it's worth answering completely. Maybe there's not an aging-related answer, but if there is one, I doubt it requires a ridiculously detailed examination of aging; it'd probably be a single physiological change that sometimes happens with age (maybe not for everyone). For example, some people end up with drier eyes. – Jefromi♦ ↵ 18 hours ago

@Jefromi That is an argument ad absurdem, otherwise every question would have to answered with the fundamental governing quantum mechanical equations. – SAJ14SAJ ↵ 18 hours ago

@SAJ14SAJ You are reading "completely" way, way too literally, making your resulting argument absurd. But it is no more ridiculous to say "aging eyes/tear ducts are often drier, resulting in less crying from onions too" than to say something about syn-propanethial-S-oxide. – Jefromi♦ ↵ 17 hours ago

@Jefromi: I rather disagree. An answer about syn-Propanethial S-oxide may sound a lot more obscure, but it's information about the onion. An answer about what happens to your tear ducts with age has nothing to do with food. – Aaronut♦ ↵ 12 hours ago

@Aaronut Fortunately we don't just answer questions about the fundamental properties of onions in isolation, we answer questions about humans using them in kitchens and eating them. – Jefromi♦ ↵ 12 hours ago

@Jefromi: The culinary use of onions does not encompass the effects of aging on human tear ducts. That's a question about biology, not cooking. – Aaronut♦ ↵ 12 hours ago

@Aaronut So you must think this question should be closed then. I would welcome an explanation on meta about this, especially if it makes it clear why this is bad but questions about taste perception and the nature of ingredients are about cooking (even if the explanations require chemistry or biology). – Jefromi♦ ↵ 11 hours ago

@Aaronut The answers (whatever they may be) come after the question. The question (despite the use of the word immunity) isn't a "health" question at all. It is a question about a completely normal (and perfectly healthy) response to a very typical culinary activity. – Jolenealaska ↵ 11 hours ago

@Jolenealaska No, I didn't really think there was anything wrong with the question. I just didn't agree that it was necessary or helpful to go into a series of hypothetical biological explanations about what might alter a reaction. This answer was at the appropriate level of detail, i.e. explaining the actual mechanism that causes crying from onions and how it might be a tolerance to the sensation but not to the chemical itself. – Aaronut♦ ↵ 10 hours ago

C'mon ... a 1999 article about onions? There was a group that showed that the process is not that simple, and even won this year's Ig Nobel for Chemistry – Joe ↵ 47 mins ago

Was 1999 a bad year for articles? Was it an uncredible source? Seriously, I read the new linked abstract (I don't have access to the full text), and while it expands the detail of the mechanism, it doesn't change anything fundamental--certainly nothing culinary, and nothing about the reflex reaction to the trigger of the tearing and burning sensation. Its import is that it might be possible to breed or engineer a tear-free onion, but that wasn't the point of the question. – SAJ14SAJ ↵ 44 mins ago

@SAJ14SAJ : see the Ig Nobel writeup : CHEMISTRY PRIZE: Shinsuke Imai [JAPAN], Nobuaki Tsuge [JAPAN], Muneaki Tomotake [JAPAN], Yoshiaki Nagatome [JAPAN], Toshiyuki Nagata [JAPAN, GERMANY], and Hidehiko Kumgai [JAPAN], for discovering that the biochemical process by which onions make people cry is even more complicated than scientists previously realized. The problem w/ 1999 is that it's dated, and been replaced with a more complete understanding of the process. (that there's other enzymes involved) – Joe ↵ 42 mins ago
upvote flag @Joe The ignoble site points back to the same abstract I already read. It may be slightly more complex, but it is not significant complexity in the context of this question, at least as described in the abstract. – SAJ14SAJ ↵ 39 mins ago edit

@SAJ14SAJ : but it still makes the part you quoted wrong. "The sulfenic acids, in turn, spontaneously rearrange to form syn-propanethial-S-oxide, the chemical that triggers the tears." They don't spontaneously rearrange, but are due to lachrymatory-factor synthase. – Joe ↵ 32 mins ago

@Joe Edited.... – SAJ14SAJ ↵ 19 mins ago

2 Answers 2


Yes, we should answer questions about biology if they're useful in a culinary way.

We answer questions about making food, including explanations of the reasons behind things, and sometimes we have to find those reasons in biology or chemistry. This is nothing new. This doesn't mean we should accept all tangentially food-related biology questions (e.g. "how do cow stomachs work?"), just that we should answer culinary questions, whether or not biology is required. And onions making you cry while you cook with them is a culinary topic.

I could make the list longer, but I hope the familiarity of this kind of question is enough to demonstrate that they're commonplace. Some are chemistry, some are biology, some are about what's happening in the food, some are about what's happening in the equipment, and a couple even have something to do with the person doing the cooking or eating.

The question that set all this off is somewhat unusual in that it deals with the science of what happens to you when you're cooking. We often talk about what happens to you when you're eating (taste/perception). We often talk about the entire life of the the food (science behind ingredient selection and the entire cooking process). We often talk about the equipment used to accomplish things which may have scientific reasons behind them.

One of the things that's always made our site great is that we talk about the reasons behind things. The fact that onions make people cry is an everyday part of cooking. They clearly affect some people more than others, and asking why that is seems completely reasonable to me. We can talk about why some pans deal better with acid than others, why not why some humans deal better with syn-propanethial-S-oxide?

The "it's biology, not cooking" argument here, in my view, isn't a useful one. There's a set of topics we can discuss, and that's always included the underlying reasons. Sometimes they happen to biology or chemistry. What matters is the question itself. We cover everything from picking out your ingredients and tools, through all the things you do in the kitchen, to the nature of the finished product. If your question is about one of those steps, I don't care if you need biology or chemistry or astrophysics to answer it, it's on topic.

And as for this specific question, essentially "what factors would make someone more or less affected by onions?", I think it's totally fine. The question "how do I avoid them making me cry?" is absolutely culinary; it's part of cooking. "Why do they make people cry?" is part of that question; again, one of the great things about our site is that we don't just answer, we explain. And "Why do they make some people cry more than others?" is just a more detailed version of that question. It's not an extra step away, it's not non-culinary, it's just part of fully understanding. We can ask "why might my souffle fall one day but not the next?", or "why do cast iron pans (but not other pans) do weird things with acid?"; "why do I not cry when cutting onions?" is a very similar question, that just happens to have human biological reasons behind it.

  • I'm trying to figure out how astrophysics comes into it, and not having much luck. Physics, sure. (and unfortunately, I can't ask any of my astrophysicist co-workers, as our offices are all shut down right now; I'm only allowed to go in to deal w/ space weather)
    – Joe
    Oct 8, 2013 at 15:16
  • @Joe I seem to remember you writing an answer about solar weather in the context of solar ovens which I think is perfectly wonderful (even if the true answer is that the actual effects are pretty small).
    – Cascabel Mod
    Oct 8, 2013 at 15:17
  • ah ... right ... I had completely forgotten about that one. (although the solar physics community doesn't like being lumped in with the astro community too much ... even if SPD is a division of AAS, they don't socialize that much; you're more likely to see 'em with aeronomy folks.
    – Joe
    Oct 8, 2013 at 16:45
  • All of your example questions are actually about cooking (or food). You're drawing a comparison to explanations for food/cooking questions that involve chemistry. That's not the same as asking questions about biology. The fact that the chemical in onions that makes people cry is syn-propanethial-S-oxide is relevant to the question; whatever biological differences in people that cause some people to react differently is unequivocally not about cooking.
    – Aaronut
    Oct 9, 2013 at 2:32
  • I really can't figure out why you've become so invested in this. Cooking is a chemical process. Of course answers will involve chemistry. Biology isn't part of the process, unless you're talking about the biology of the food itself (i.e. food safety). This site was never about "what happens to your body when you cook/eat some food" and we've always, always closed questions along those lines.
    – Aaronut
    Oct 9, 2013 at 2:35
  • @Aaronut I can't figure out why I set off a huge response here. Why in the world is it okay to ask what that acid is doing to your cast iron (making it maybe unsuitable for cooking) but not what that onion is doing to your eyes (forcing you out of the kitchen)?
    – Cascabel Mod
    Oct 9, 2013 at 2:47
  • It is on topic to ask what the onion is doing to your eyes, that's the point you seem to be missing. What's off topic is speculating at length about why certain people have slightly different reactions to that specific thing that the onion is doing to their eyes. And unlike a question about "how to avoid crying" which might involve rather non-culinary-sounding answers like "wear goggles", this particular example deals entirely with theoretical concepts (of a non-culinary nature) and therefore doesn't present any obvious benefit to our expected audience.
    – Aaronut
    Oct 9, 2013 at 23:27
  • To make it really simple: We've always been, and still are, largely okay with questions that are one step removed from practical culinary knowledge - "why does this happen" or "can you cook a whole fish in a dishwasher" or "how much potassium is in X", that sort of thing. Two steps removed is too much; it's the same category as the other areas we avoid like general health/nutrition and legal questions.
    – Aaronut
    Oct 9, 2013 at 23:32
  • 1
    "Why does my cast iron pan but not my stainless steel pan do X when I put Y in it (in the process of cooking)" is the same number of steps away as "Why do my girlfriend's eyes but not mine tear up when I put onion vapors in them?".
    – Cascabel Mod
    Oct 9, 2013 at 23:57
  • It seems that the core disagreement here is that you think that eyes tearing up when cutting onions is nonculinary. I think that it is culinary, because it's something that's inextricably a part of cooking. Sure, the onions don't care if you cry, but saying that understanding the phenomenon (as part of dealing with it) is nonculinary and we should only ask about avoiding the crying is like saying that understanding how grease fires work is nonculinary and we should only ask about how to put them out. "Why?" is important. It's part of the same question/answer, not an extra step away.
    – Cascabel Mod
    Oct 10, 2013 at 0:01
  • @Aaronut I've tweaked my answer slightly to emphasize that I'm not saying that all food-related biology is on topic (not all food-related questions are on topic in general). But throwing something out just because it's biology is still bad.
    – Cascabel Mod
    Oct 12, 2013 at 17:11

When the topicality of a question is in dispute, when reasonable people disagree, I think it is always best to err on the side of allowing the question. I'm not saying that because the question in question happens to be mine, but because I think the issue is a pretty simple exercise in harm reduction. What is lost by closing a question that may have ultimately provided a fabulous answer is greater that what the site loses by allowing a "borderline" question.

  • Filling the site with questions that are noise rather than on topic is also harm.
    – SAJ14SAJ
    Oct 12, 2013 at 13:52
  • That's why I included the "reasonable people" caveat.
    – Jolenealaska Mod
    Oct 12, 2013 at 13:56
  • 1
    I think it's good to err on the side of allowing the question all else equal - but sometimes all else isn't equal, as SAJ14SAJ suggested. Still, it's really easy to start worrying way, way too much about opening the floodgates, when in practice, it's likely just going to be a couple of questions. And honestly, it's not like these policies have to last forever. If we realize that by allowing this one onions and eyes question, we've allowed 10000 biology questions and people actually start asking them, we can revisit it. Otherwise... keep calm and enjoy the useful posts.
    – Cascabel Mod
    Oct 12, 2013 at 15:29
  • @Jefromi That said, you won't even negate the downvote?? PFFT...See how you are? <insert appropriate emoticon here>
    – Jolenealaska Mod
    Oct 12, 2013 at 16:19
  • @Jolenealaska I think in order for this to be a useful answer to the question, you need to make the case that this is indeed a borderline case where "err on the side of on topic" makes the difference. I think culinary questions about biology are clearly on-topic in general, but Aaronut thinks they're not actually culinary - you'll have to do more than push things across the border to convince him!
    – Cascabel Mod
    Oct 12, 2013 at 16:59
  • Oh jeez, you're asking for actual work. Alright, after a good day's sleep.
    – Jolenealaska Mod
    Oct 12, 2013 at 17:17
  • @Jolenealaska Sorry! I do think this is all true (with caveats, as in my previous comment). And I do appreciate the sentiment, since I think sometimes we're too eager to make and enforce rules trying to solve a nonexistent problem - throwing the baby out with the bathwater, then realizing there wasn't even any bathwater.
    – Cascabel Mod
    Oct 12, 2013 at 17:26

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