Fetuses as Innocent Bystanders

Judith Thompson argues that a fetus does not have the right to infringe upon its mother's right to survival. However, what if the infringing was being done not by the fetus directly, but instead by a deadly gene? Consider a hypothetical gene that causes the fetus to indirectly kill the mother at birth, yet allows for the baby to be delivered properly. The fetus did nothing to receive such a gene, it was passed down by its parents. Would this hypothetical gene still be infringing upon the mother's rights? What if the mother herself new that such a gene existed in her own DNA? The point is that the fetus may not have an entitlement to the mother's body, but neither is it responsible for this infringement. In other words, to give the fetus personage would be forcing us to make it an innocent bystander in this scenario. The fetus does not leech resources from the mother because it has the active will to do so, it is merely wired to do this via its genes. It does not make the choice to become a parasite to the mother's body. Since it does not (cannot) bear ill-will towards the mother it is a bystander. Therefore, it is fair to conclude that to undergo an abortion would be the equivalent of killing an innocent bystander. Normally, to prevent this, we would simply avoid the case where the mother endangers herself, but this is not possible because she is pregnant. To avoid this scenario after conception would be to get an abortion. Yet, to get an abortion would be to kill an innocent bystander. I believe to argue for abortion we should abandon that a fetus (or later stages of a fetus) may have personage and argue that it does not, and so in certain situations abortion is perfectly acceptable.