Wrinkles are just layers of paint.
I'm painting a new painting on top of another painting. I've done it a few times to this particular painting. It now has developed some interesting wrinkles because of the different layers of paint going different directions.
It made me think of when I was a child and we painted our house every year. It would develop an interesting look. Sometimes we would strip off the paint to the wood and repaint.
A child starts out as a new painting. As they grow older, they start to develop their own story. As they age, their story changes applying another layer of paint. Each different story through their lives adds yet another layer.
The next time you look at a face, just think of the stories painted onto that face.