Another version is to look at my reactions to other people and see what they say about my self image. One conclusion is that my subjective age is substantially lower than my objective age. The people I intuitively react to as my age peers are in fact noticeably younger than I am.
I have a simple explanation for this pattern; if it is correct, it should apply to most people, not just to me. My self image is based on some sort of weighted average of my experiences over the years. An average from, say, age ten to age 62 is going to come in at less than 62--considerably less unless very heavily weighted towards recent years.
I have, however, an alternative explanation based on experimental data from a very long time ago. At various points in my teens I was a camp councilor. I observed that if the campers in my cabin were, say, eleven year olds, anyone from about fourteen up felt to me like a grown up. The older my campers, the older my subjective definition of adult. Currently a large part of my social interaction is either with my own children--13 and 16--or with the law students I teach. Perhaps that shifts up my subjective experience of the age of people much older than that--even if they are younger than I am.
Anyone else have evidence to offer? Conjectures? Should I blame it all on neoteny?