There's an idea called "Self-concept", which is basically the collection of thoughts that make up your core identity. Eg "I am an American, Democratic Stanford Graduate." Note that these attributes don't have to be comprehensive, or even true-they're just the core beliefs you have about yourself.
Self-concept changes, but rarely, and usually more due to a few big experiences than over time. So in "permanent age" terms, you're more likely to go from 42 to 18 or 12 to 26, than you are to go from 42 to 43.
Self-concept changes, but rarely, and usually more due to a few big experiences than over time. So in "permanent age" terms, you're more likely to go from 42 to 18 or 12 to 26, than you are to go from 42 to 43.