Ethics is a slippery slippery subject. Why? Everybody has a personal ethical, or perhaps two stances.
Many possible stances are combinations of three basic sorts of ethics.
Deontological. Follow the laws handed to us. Don't kill, don't steal, don't force people to incriminate themselves.
Utilitarian. Choose a path that yields the greatest good.
"Responsible". Choose a path that yields the greatest good, but excluding one's own welfare. "Nobody has greater love than to lay down his own life for his friends'" We make heroes of people who act on this stance.
When an abstract situation presents itself, most people I know go for the utilitarian stance. How can I drive the bus with the failed brakes to kill the fewest people? Fine. Big whoop.
But, when presented with a real situation, people gravitate to their deeper stances. "Dad's not going to regain consciousness. Should we ask the hospital to shut off the respirator?"
The deontological stance often says, "NO WAY! DAD DESERVES THE BEST CHANCE." In Judeochristian terms, this is translated "choose life."
The utilitarian stance might say, "that respirator is expensive. Could those resources be spent curing someone with a long life ahead of them?" Health insurance companies are 100% utilitarian, and that often comes across as offensively callous. It's not, really. It's just an ethical stance among many.
The "responsible" stance recognizes Dad's agency. It might try to ask what course of action is kindest to Dad, even if it's frightening to his children.
Obviously there are lots of nuances in these real situations. No actual situation comes out like a case study. In the work of practical ethics, it's important to work with people to help them discover and express their own deep ethical stances.
I said people have two stances, because peoples' stated, intellectual, stance is often not quite the same as their deeply held, operational, practical, stance. Both levels count, because people use their intellectual stances to unpack and grapple with their deep stances. That unpacking is some of the hardest work each of us will do in our lifetimes.
Is this all postmodernist relativist claptrap? Is it all age-of-uncertainty hogwash that ignores core human values? To many who hold strong deontological stances, the answer is yes. Can it justify genocide? Certainly not, because genocide necessarily denies the agency -- the ability to act upon their own stances -- of an entire group of people.
The philosophers of ethics do well when they help us tell the stories of our own stances in ways that help us do the hard work of confronting our own deep ethical stances when circumstances force us to do so.