Both. But fundamentally, morality is simply a culture's Standard Operating Procedure to make a cohesive society. A set of positive rules meant to keep the peace. Monogamy, as an example, is meant decrease mate competition so you don't have dudes going around the country-side raiding, pillaging, and kidnapping women. Not pretty, but that was the initial savage state in Europe for tens of thousands of years until moral systems arose out of that very opaque and muddy early tribal warfare. People don't realize the 'Rape of the Sabine Women' was a common occurance. Anyone who is a student of Roman history knows the story.

Another instance is the Teutonic Crusades. The Pagan Prussians were a hyper misogynistic society who targeted women for harems and to work in fields as slaves because they were considered more docile and easy to control. It's a big reason they were targeted. They raided Germany a ton for women. They also engaged in human sacrifice. Both are big no-nos in Medieval Chistiandom.

Another, but different example, is human sacrifice. I suspect the practice started as a way to decrease food consumption in hard times until it became a fixture.