Why not have both? Because the game would not know whether the Sim is the one to get pregnant or to get someoen else pregnant during the woohoo. How would the game decide to determine if she is getting pregnanat or causing someone else to be pregnant. That code might be too much trouble. And if it was all set on chance and random, and a percentage, then someone would complain one is always the one to get pregnant and not the other. It's best just to try to mod it and let them worry about bringing bigger EPs to TS4 because it sure needs them.
