What makes a person the same through the years, when the appearance changes?

What makes that we see ourselves the same through the years. While when you see somebody, whom you haven’t seen for years, says that you have changed. But he recognized you. How did he recognize you? What stays the same through the years? Your appearance? Your soul? Your behavior or how you react to events? Or your identity? But what is identity then? Through the years you learn think about yourself. So for instance you used to be shy, but when you get older this change and now you do dare to talk in public or to say your opinion. But is this your identity? And where is your identity? In your appearance or in your genes? Humans are made out of thousands of cells. These are repaired and renewed many times through our lives. The cells of the human body are at the end of our lives almost completely replaced compared to when we were born. Is a man then, apart from all the knowledge and experience, when he dies still the same as he was born?
Greek philosopher Plutarch tells of the legend of the ship of Theseus. This ship is sailed, in gratitude to Theseus that he has slain the Minotaur on Crete, every year to the island of Delos. After years the planks got rotten and replaced. Until no more plank is original. The ship still looked exactly the same as the original ship of Theseus. Since this is a slow process, we will not doubt that it’s still just the ship of Theseus. But imagine that behind this ship sails a ship that captures all discarded planks and create a new ship with them. Now, there will be two exact the same ships sail into the harbor. Which ship is the ship of Theseus and may claim the identity of the ship of Theseus?
This can also involve to our people. Are you over the years, still the same person? And what makes this person this personality?
This period I have done a trail with the thought experiment of the schip of Theseus. For this, I made three fingers of a body material. One finger of three different ages. A child, a middle-aged and older person. Which finger contains the most identity? Fingers hold the power to feel, to create and to make, but they also include your fingerprint. Is this your identity? Where is your identity placed? If you look at your body through your skin, blood vessels and muscles, you come to your bone. Is it there? With this jewel, I want to ask the audience the question what makes a person the same over the years, as the appearance changes?