That, and potentially Knowledge. Being educated could make sense as a background trade, but Knowledge skills can have a pretty tangible effect in combat.
They can, but should they? I don't think how Knowledge works right now is good for the game.
A PC approaches a monster, and the player recognizes the hints the DM dropped. Only comes out at night or when overcast... noble's house with windows shuttered, and no mirror to be found... he approaches the creature, AND! fails the Knowledge (religion) check, so must pretend he does not know it is a vampire. Its just as bad the other way around, too. The PCs are surprised by the Bugblatter Beast of Traal, and the guy with Knowledge (nature) rolls high, so the DM must stop and explain what this thing's weaknesses are, and the player starts making battle plans OOC because in-game the PC knew what the beast was all along, and recognized it from his prior studies.
I recommend removing Knowledge altogether, and let the DM decide what the PCs should know, as appropriate to his campaign. If the setting's religions, nobility & royalty, history, local culture, or
whatever is relevant to the plot, the DM will give his setting document to the players and if the player remembers a detail from it during a game session he may use it, no roll required. Likewise any sourcebook has an in-universe Equivalent, so if the players can know it the PCs can know it too. If the DM wants something to be a secret, he won't share it with the PCs, and if the DM wants to leave it up to chance Gather Information can be used as a substitute for the occasional use of Knowledge. The knowledge skill uses that aren't "know about X" are folded into other skills, and things that give Knowledge bonuses or bonuses based on Knowledge get removed or replaced.
2. Cut some excessive skill choices for "flavor".
Another option is to have two pools of skills. One could be close to what they are now, called Skills, and the other could be the more flavor-oriented ones, called Trades. This would allow people to put some mechanical representation of the fact that they have a background in hunting, blacksmithing, or underwater basket weaving on their character sheet without dipping into the same pool that fuels Knowledge, Concentration, and UMD.
Yet another option is to eliminate "fields". For example, instead of Craft, Profession and Perform, I use just two skills: Trades and Performer. Trades covers whatever sorts of background professions the character has: a PC tradesman can be the butcher, the baker, and the candlestick maker at no extra cost, and if the PC tradesman wants to acquire a trade he didn't already practice in the background, he roleplays out an appropriate training sequence and adds it to his list at no cost. Likewise, a Performer can know how to play string instruments, wind instruments, dance and sing as a single skill, or whatever else he uses in his performance. This is simpler than using two pools of skills, and I think the combined skills are useful enough to compare with adventuring skills.
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My own approach to skills is to combine skills into a shorter list (23 skills), and to give everyone the same number of skill points per level (5) no matter their class or int score, and eliminate the class/cross-class distinction (everything's a class skill for everybody). Thus skills are effectively separate from the class system, and nobody is shafted.