I like to do away with vague metaphysical terms like “intrinsic”, especially with the question of if morality is intrinsic. It’s not precise enough.
For people who kill like ISIS and for people like us who feel disgust, it seems to be how our brains and the environment we live in deciding the morality of things.
I haven’t read Friedrich Nietzsche work featuring the “Will to Power” concept yet but he mentioned another concept the “Master – Slave morality” and this is where I see how his idea is true. Perhaps there is no morality, only Power that comes in the form of survival of the fittest for individuals, working together for groups that are weak individually and the Justice system to keep the individuals and slaves in balance. If there is no Justice system in place, then there will be anarchy and the ruling Elites would lose profit/ control. The Masters in the modern context are the company CEOs, Politicians, Aristocrats etc while the Slaves are the working class, the poor, you and me, the soldier sent into the front lines to die for the sake of occupying foreign land for oil/ diamonds/ gold/ land etc.
Monkeys show similar behaviour to us because an experiment was conducted in which two capuchin monkeys were given a type of food; one monkey received a grape every time it cooperated with the Scientist whereas the other monkey only received cucumbers whenever it cooperated. After this experiment was conducted many times, the monkey that only received a cucumber began to realise he/ she was being treated unfairly because he/ she was aware that the other monkey kept receiving the grapes so he/ she responded by throwing the cucumber back at the Scientists. This explains why there are groups like Occupy Wall Street and other groups that are Left wing/ Socialists.
Of course, some philosophers say that morality is an emotional reaction, though I can’t remember the philosopher who said this, which is true because upon reading the first few pages of a book called “Confessions of a sociopath” by M. E. Thomas, she stated that when she found a baby Opossum struggling to swim to safety in the pool, she decided to kill it by submerging it with a net but gave up, letting it die a slow death. She didn’t feel any guilt, no remorse, no empathy for the animal, only that it was an inconvenience and needed to be gotten rid of so that her pool could be disinfected and used for a swimming lesson. She saw no benefit in keeping it alive. The same goes for serial killers like ISIS/ IS, the criminals in the big city etc.
There is also the cultural and environmental element involved as well; some cultures regard certain practices as acceptable while others don’t like Honour killings, marrying cousins etc while children or adult born or conditioned in an environment that is violent are likely to be violent.