One little change can alter the path of a life but personality remains remarkably consistent throughout.
In my life, there have been swings back and forth between various interests rather than a single stright forward path. For example, though I've always been interested in photography, my level of commitment to it has ebbed and flowed depending on other life circumstances and available time etc. I got a master's degree in biology and an MFA in writing, but continue to be interested in both, though the interest rises and falls with the rise and fall of other interests. Same thing with skiing , motorcycling and so on--they also ebb and flow with the different companions I have. I skied a lot as a child, then didn't for while, then cross-country skied with Bruce, then added downhill skiiing with Chuck, and now rarely ski with Keith. I motorcycled with Peter and Michael and then did not for years, and now I am motorcycling again with Keith.
Apparent personality does change somewhat as we grow and mature, and also as we age and grow tired, but many aspects remain consistent throughout. In my case, having insomnia and sleep apnea has robbed my of some of the abundant energy, enthusiasm and joy I used to have and made me more sluggish and grumpier, changes I am not proud of! On the other hand, I am more patient, tolerant and forgiving, in some ways, than I was when I was younger.