For the Radio Studio, Charisma (C) is the key stat. Dwellers with high Charisma assigned to the Radio Studio will attract new dwellers from the wasteland more frequently. For reproduction in Living Quarters, Charisma also plays a role in how quickly dwellers 'get to know each other' and become pregnant. While not directly impacting resource production or combat, Charisma is essential for growing your vault population and maintaining high happiness. Train a few dwellers specifically for high Charisma to staff your Radio Studio and to facilitate efficient breeding programs when you need to quickly increase your dweller count.
