Question

Are all mutations in DNA passed on to offspring?

Answer 1

I will No, not all mutations are passed onto offspring. I will assume Only mutations in the DNA of the gametes (sex cells) are potentially capable of being passed onto offspring.

Explanation:

Let us assume that answer is being asked with respect to eukaryotes.
A mutation is a change in the genetic code. It consists of an alternation of nitrogenous base, a deletion or insertion of a base in the DNA molecule. Only 5 % of our human DNA is expressed, so mutations that occur in the remaining 95 % of the DNA are innocuous. If these mutations occur in somatic cells (body cells) then, they will not impact the future offspring. Only mutations in the DNA of sperm cells and egg cells will potentially affect offspring.