Mentat (popular poster here) asked the question to the effect of "Why does a given stimulus give a (negative) response, and why specifically is it different in people who are genetically very similiar?" I thought the information I could provide was enough to warrant a new post. Here it goes: The best and most logical way to go about this is to follow the sensational path of the experience. Let's use green beans. There is a few ways this experience can occur 1. One can smell green beans - and have the negative response 2. One can see the green beans - and have the negative response 3. One can taste the green beans - and have the negative response 4. One could hear a mention of them - and have the negative response 5. One could seemingly randomly have a "green bean" thought - and have the negative response To handle the first 4 in one punch, we will generalize terminology. First there is a piece of sensory information which enters the appropriate sense organ (a smell, sight, taste, or audio). Once The information reaches the appropriate part of the brain for that sensory piece, it is immediately compared to all previous records to see if it is new or old information. Some points to understand: One of the brains most important ability is to compare incoming data with the entire memory. When more than one function occurs in the brain in unison, one of those events begins to more easily activate the other neural function. It's the ultimate function of conditioning. So when the information goes in, the brain compares it, and if it is repeated information, the brain, will either purposely reproduce the other neural functions which coincide with this information, or it will do them seemingly "on it's own" reletive to the wants of the person. So for instance, if someone asks you "What are 5 countries in north america" you will purposely search for information which is neurally linked to this input. However, sometimes when someone will say something that bothers you, it will result in bad feelings, conditioned feeling! Get it? OK So, the input information triggers other information to be accessed. At this point something interesting happens. Let's say the smell of green beans is something mentat doesn't mind - he just hates the taste. The smell input might trigger the taste memory!!! Now what would happen if mentat would eat green beans? The taste trigger would activate - so what happens is the smell triggers the taste memory, and mentats brain almost is tricked into thinking it has just tasted green beans - because the memory is still conjoured identically! Usually the other-sensory information is not conjoured as "powerfully" as if it was the primary sensory information. This explains why most people can handle this, while some will gag and have negative sensations; some things are more "sensitive" to them. So this explains why the negative information occurs. You can surely understand why the memory itself would trigger the sensations. The brain works as a neural network - and this has been proven. Things that have been experienced as having a relationship are linked - the stronger the relationship the more close and strong the link. One can easily link FISH with OCEAN. But one might be less likely to link the color PINK with SALMON, which is a FISH in the OCEAN. When links aren't used - they diminish. This is how we lose information that is indeed still in our brains. The ITEM is NEVER LOST, the link just breaks down. So what about a genetic predisposition? Indeed siblings seperated at birth have been found to like and dislike certain things. Sometimes these things are as simple as a particle food they like or hate - and sometimes they are as complex as having the same job or hobbies, or liking the same qualities in a mate!! Now, what this means is the genes which involve the development of the brain must have same relationship with neural pathways and networks. Beyond that it is a very difficult question, and not yet answered. The specific physical position of every piece of the brain is directly linked with every aspect of the brain - what is in the memory, what someone is "better" at, and indeed someones personality. Every single connection is an important part of someone - and these connections are a function of the gene instruction for development, and the connections made and broken by environmental sensory experiences. One more issue exists - which is why does something cause a negative or positive response? Well - for a completely unique experience, we can almost always trace it back to childhood. We all had to eat green beans at some point as a kid. It's merely a matter of conditioned response, and really isn't as much a mystery as some would like. EVen if a child has one negative experience with the taste of something, it's most likely the child will never want to eat this food. One fact is extremely important. One of humans majors errors is thinking that two people experience something at all similiar. No two people taste something the same way, no two people hear something the same way, and no two people see something the same way. Most people would think that if two people listened to a song - they are hearing the same thing. But in fact they are not. Why? Well there ears essentially hear the same, but you must remember someone does not hear something, so much as they HAVE heard something. You cannot know what you've heard until AFTER the stimulus has gone through parts of the brain that are BIAS. These bias parts of the brain (which is nearly all parts of the upper brain) is the entire explanation why people can never agree on matters of opinion: What is beautiful, what sounds pretty, what sounds bad, what feels good, what feels horrible. What scares me and what doesn't scare me. That explain alot, and keep in mind that last part. You may wonder why someone can not like a song you think is the best thing you've ever heard. The reason is because they are not hearing the same song as you. I know that is hard to believe, but it is the function of our brains being unique and terribly bias. Anyone get this far? Lemme know what ya think!