Why can cocoa butter vary depending on where cacao was grown?

The properties of cocoa butter vary depending on where the cacao is grown because the specific combination of fatty acids within its triacylglycerols (TAGs) differs by region.1

Cocoa butter is composed of palmitic, stearic, and oleic acids, which form the TAGs responsible for the fat's characteristic solid state at room temperature, as well as the creamy mouthfeel and snap of chocolate. Because these fatty acid profiles are not uniform across all growing regions, the resulting cocoa butter can exhibit variations in its physical properties.1