It’s the example I point to as where my database helps, so I can track these things, because I had ages ago, listed a more generic shellfish allergy. This was after cursing Google for pushing diarrhea cures when I wanted to trigger it… go figure.
When I do want to bring some significance to a character, I’ll roll the dice, effectively, and run a utility I have that picks random lines out of a file. I’ve got files for personality traits, hobbies, allergies, occupations, and phobias. So, I’ll pick, say 10, and see what makes sense, and create a character for that. I use the random thing, since although it’s easy to say “I want the character to have flaws”, trying to pick those traits while also not overusing a few favourites, that’s tougher.