"Of course it's wrong to beat your wife!" says the person who beats their children in a society that has only recently ceased infantilizing their women (USA circa 1900 +/- 30 years).
"Of course it's wrong to own slaves!" says the person whose society only recently began protesting against and/or illegalizing slavery (USA circa 1866 +/- 10 years)
They say this not knowing that had the event of their births been moved a few decades in the wrong direction their morality would have shifted with it.
Those same people might have said "Of course its wrong to beat your wife with a rod thicker than your thumb!" or "Of course its ok to own slaves as long as you treat them well!" at the same point in their lives had they been born maybe 30-50 years earlier.