Age 14 to 77

The suggested articles that DuckDuckGo puts in front of me includes this claim that our personalities change to unrecognisability from age 14 to 77. Except in my case that is not even close to true. The study speaks about teachers rating Scottish 14 year olds in 1950 on a variety of attributes that they summarise as "dependability," then following up on that decades later, with self-report and friend report of that percentage of subjects they could track down.

Fourteen-year-olds are generally not dependable, and even the component parts of that seem to my eyes to be highly subjective, depending on the sorts of things teachers like to see, rates of physical and emotional maturation, and cultural accidents such as who you have in your class and what siblings have had this teacher before. This is not good initial data, which is what you are hoping to compare to years later.  I think running that data on 10-year-olds would have given you more stable results, because puberty wouldn't be interfering. Ages 12-15 are very much a moving target.

Plus they had been through a war and economic restrictions quite recently, far more lengthy and extensive than anything we are facing now. Dad might have died, and you are still in childhood. That might matter. I don't know that, but it's worth keeping in mind.

At the other end, the data at 77 on how "dependable" you are is going to be heavily influenced, both in your estimation and your friend's, with what you have accomplished in life.  That will of course have some correlation to your personality, but halo (or trident) effects that include your intelligence, your luck, your external circumstances, and recency bias will color, or colour, those evaluations.

At fourteen I was highly conversational, friendly and complimenting others, with a constant stream of interrupting others to clarify what they were attempting to say and the word they were seeking, with creative solutions verbalised, daydreaminess and difficulty focusing on a topic for long. I sought new intellectual but not physical experiences (relatively.  Teenage boys do just do that excitement-seeking thing.) As to Big Five traits, I had high agreeableness and moderately high neuroticism.  I would likely score higher on conscientiousness now than then.  I suppose that's different, but compared to others my age, then and now, I don't know that there's going to be something measurable. Other than that last I show dramatic similarity, and people at reunions often comment on it.

Let me tell you what I think is going on with studies like this, other than a simple desire to publish something to keep your job at university. They want to create a bank of supporting evidence that Eastern religions are truer than Western ones.  That may not be conscious or explicit, but it is showing up in the social sciences a lot these days. They don't like the ideas of legacy and cultural continuity. They like to think they made huge changes and improvements after their (delayed) independence from their parents and then their divorce.

While I am deeply humiliated by the 14 y/o I was, I also still like him.  I'm not sure that's true for people doing studies like this one.