Like others have said, mutation has to be in the green cell you're passing on. Also note that germcells are haploid, you could inherit one or the other allele, for CF this is important. Following the Lamarkian idea if passing on traits acquired during life, were talking epigenetics. This can turn genes in or off via mechanisms like chromatin methylation and acetylation. Fascinating field, I ran a small epigenetics core at Vandy long ago.