We report the first measurement of the (e, e p) reaction cross-section ratios for Helium-3 ( 3He), Tritium ( 3H), and Deuterium (d). The measurement covered a missing momentum range of 40 ≤ pmiss ≤ 550 MeV/c, at large momentum transfer (Q 2 ≈ 1.9 (GeV/c)2) and xB > 1, which minimized contributions from non quasi-elastic (QE) reaction mechanisms. The data is compared with planewave impulse approximation (PWIA) calculations using realistic spectral functions and momentum distributions. The measured and PWIA-calculated cross-section ratios for 3He/d and 3H/d extend to just above the typical nucleon Fermi-momentum (kF ≈ 250 MeV/c) and differ from each other by ∼ 20%, while for 3He/3H they agree within the measurement accuracy of about 3%. At momenta above kF , the measured 3He/3H ratios differ from the calculation by 20% − 50%. Final state interaction (FSI) calculations using the generalized Eikonal Approximation indicate that FSI should change the 3He/3H cross-section ratio for this measurement by less than 5%. If these calculations are correct, then the differences at large missing momenta between the 3He/3H experimental and calculated ratios could be due to the underlying N N interaction, and thus could provide new constraints on the previously loosely-constrained short-distance parts of the N N interaction