Stan's dad death

Holy shit I never thought of this. So Stan and Ford's dad most likely died sometime in the 30 years where Stanley was pretending to be Ford. So if Stanley faked his death, his parents probably assumed he was dead as well. So if the twins are around 60-70 years old, it's safe to say their parents have died. So that would mean Stan's dad died thinking one of his son's died... That's really depressing