system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can sunburns and sun exposure cause permanent skin damage if your skin is constantly replacing itself?

Recently read something about how a few bad sunburns when you're young can cause a large increase in cancer later in your life. How can you develop cancer several decades after you're burnt if your skin cells are constantly dying, falling off, and regrowing?
gpt
One of the best ways to think about it is not as "sun burn" but as a radiation burn. The skin is constantly replacing the top layer but more severe burns penetrate deeper into the skin and surrounding tissues. Sometimes this can damage the skin all the way to the lowest skin layers and when the tissues heal scarring forms as the skin cannot adequately regrow across the  urn.