We're The Chemists Who've Found The Formula

For some reason I decided to read the Atlanta paper this morning. It's in my newspapers folder, but I rarely get to it, seeing as I start at the bottom with the Starkville Daily News. But this morning I'm irritated at Mississippi State and just want to calm down, so i read the AJC. And there I found an article on "umami" (link in title).
Umami is the "fifth taste"--the Mmmmm factor that can't be explained by salty, sweet, sour or bitter (am I alone in thinking that bitter should start with an "s", too?). It is that instant melt-in-your-mouth sensation, that one that makes you close your eyes and moan. At least, that's how I understand it.
But why is it that it's different in everyone? I mean, most people are able to agree on what is salty. People don't eat a chip and say, yum, sweet. And although there are different degrees of sourness, almost everyone puckers up a bit. But I can eat sushi practically every day, while others cringe. Ok, ok, so sushi isn't the best example. Many people simply don't like the texture of the raw fish. But I would happily kill and then walk over your lifeless body for a freshly made tortilla, and most others would be happy to lock me in a mental institution for this.
All I can think to explain umami is that it is different for everyone. It does exist--scientists have isolated the receptors that give us that rush. Yet it seems to be something we've trained our tastebuds to do. Which in a way makes sense, as if we don't eat a lot of sugar our tastebuds react differently when we do eat something sweet. So umami is different according to where you live, how you were raised, that sort of thing. In my opinion, it is also molded by the experiences we have along the way.

Here are my umamis...and the reasons I think that I crave these things:
Tortillas--they are my reminder of Mexico and Central America
Blackberries--summer picking
Toast with butter--I eat it when I need comforting
Salmon--I think it might be because it was the first "grown up" food I really enjoyed
Sushi--The thrill of trying something new, and it reminds me of fun experiences

Speaking of umami...B and I had the best sushi this weekend. We went to a storefront sushi place in New Orleans that his friend had recommended. He also said we needed to get the special. Now, I'll admit, I'm typically not the most adventurous sushi eater. I used to be content with my california rolls and maybe one similar roll. We sat at the counter and watched the chef make this giant roll, with a crab salad type mixture in the middle. Then he topped that with slabs of raw meat (turned out it was pepper-seared tuna, but we didn't know while we watched). Then came wasabi and three types of sauce, before he at last pushed it across to land in front of our wide-eyed faces. I informed B that he'd probably have to reliquish the other rolls we'd ordered, because I was not going to eat that roll. But I took a piece and mmmmmmm. The flavors went together so well. Once again, we'd made the mistake of ordering the best roll on the menu (wait, this one actually wasn't on the menu, it was a special order) and then having other rolls that did not measure up. From now on, I'm going to be more adventurous in my sushi orders.
That is, in those rare times when I escape Starkville and am able to eat sushi.