Everything is relative and everything is in the mind. In the past, children sacrifice was considered morally good because people thought it would soothe the "madness" of the gods, until someday people realized that children sacrifice was all bullshit because it didn't work most of the time.
In the past, child sacrifice was still considered a moral wrongdoing, but the people who participated in it, did not think that the God they served cared about moral wrongdoing, and only cared about the sacrifice.
I remember a social experiment in a pair of twins that were seperated and raised in different environments, one was raised in a regular family, I guess he was taught the christian morality, and the other was raised in a criminal environment with no moral. The results were what we can expect, one ended up being a "model" person and the other a fucking criminal.
Ok? Just because their lifestyles influenced their outcomes doesn't mean that they didn't have the same morals.
Again, 2 things can be true at once. People can have the same morals, but those same people might not choose to follow them.
For example, it was thought that homosexuality was inmoral, but now it's not.
A lot of people still consider it immoral. That is not a universal truth that it is now moral.