In my experience, acquired over more than six decades, I've found that very few people grow up - they simply grow old. Most people fail to perform even the most basic self-administration and most people's minds are empty of anything of interest. Therefore, it's not age that matters; it's who the person is and how they have chosen to live. The sad fact is that for any age range one happens to select, there are very few people who are worth an investment of one's time because most people simply sleepwalk through their lives.