The parents are horrific monsters (in the ethical sense) anyway, so you would absolutely not have wanted to have a relationship with the mother. The dead parents are also vitally plot-relevant. But, no, fundamentally this is absolutely not an incest game, which is why the tag is not present in the header or the OP. There is a relationship with similar emotional impact with a non-blood-related girl, though: The MC builds a romantic and sexual relationship with his unofficial adoptive mother: the woman who saved the MC from the explosion that killed his parents, and raised him since age 4.