It's my understanding that various hazards can damage the DNA in our cells, causing mutations.
But whenever I picture this, I see the damage being done to one of our tissues (for example, our lungs due to smoking, or our skin due to UV rays).
When I think about this, I see that... many cells in a smoker's lungs, or many cells on the back of a beach-goer's neck, may have mutations in their DNA. But only the cells in that tissue have these mutations... the other cells in our body would not have the same mutations.
In particular, sperm and egg cells would not have the same mutations, so the mutations due to smoking and UV rays shouldn't pass on to children.
Are there instances where mutations that occur over the course of our life are spread to every cell, including sperm and egg cells, so that every cell reflects the mutation, and the mutation is passed onto our offspring?