Despite significant progress in the realm of upper-limb prosthetic design, end-users still abandon modern myoelectric prostheses, with haptic feedback listed as a primary need. The passive scheme of cable-driven body-powered prostheses provides kinesthetic sensory information to the user but can also lead to discomfort and fatigue due to the large loads applied to the body during operation. In order to investigate the role of this kinesthetic feedback on grasp force control, we design a body-powered prosthesis emulator capable of varying the amount of displayed force feedback along a continuous scale. Using this experimental test bed, we collect data from 9 participants while they perform a grasp and lift task. Analysis shows that, with increasing amounts of force feedback, people produce lower and steadier grasp forces but also become more prone to dropping held objects. These results suggest that the use of moderate amounts of feedback provides significant grasp performance benefits while also mitigating some of the shortcomings of cable-driven prostheses. These findings support the continued study of the incorporation of kinesthetic feedback into novel prosthetic designs.