Think of this at the genetic level, not the personal level. Let's say you have a gene G, which affects decision-making about reproduction. If G causes people to decide not to reproduce, then your ancestors possessing gene G will have not reproduced and you won't exist. If G makes you decide to reproduce, then your ancestors will have reproduced and you will exist. If we interpret decisions as altering the output of the algorithm that produced them, then deciding not to reproduce can alter the effects of gene G and therefore affect your ancestors with the gene.