A population of small main-belt asteroid pairs (MBAs) residing on very similar heliocentric orbits have been found and studied recently (Vokrouhlicky and Nesvorny, Astron. J. 136: 280 2008 and Astron. J. 137: 111 2009, Pravec and Vokrouhlicky, Icarus 204: 580 2009). These asteroid pairs show some common properties: they are ubiquitous with pairs found throughout the asteroid population, pair members are separated with low hyperbolic escape velocities (as low as 0.17 m/s), they are young with most pairs probably separated less than 1 Myr ago, and their sizes and mass ratios overlap with the population of orbiting, bound binary systems. Previous investigations of binary asteroids suggests that they were formed from parent bodies spinning at a critical rate by some sort of fission or mass shedding process (Pravec and Harris, Icarus 190: 250 2007, Scheeres, Icarus 189: 370 2007, Walsh et al., Nature 454: 188 2008), however the possibility that these two populations of asteroid pairs and binaries were related was intriguing but lacked of observational data. We report on a systematic observation campaign of spin rates, relative sizes and shapes of paired asteroids which enables this population to be analyzed. Two key characteristics of the asteroid pairs population appear: the primary spin rate is correlated with the mass ratio between a pair's components, and there is a cut-off in mass ratios of asteroid pairs above a value of 0.2. Both of these results are predicted by the rotational fission process hypothesized in Scheeres (2007), and suggests this or a similar process as the genesis of the asteroid pairs and by implication as a fundamental process in the formation of asteroid binary systems. This formation mechanism is distinct from the Walsh et al. (2008) hypotheses to explain the population of orbiting, bound binary asteroid systems.