We report control of the spectral and noise properties of spontaneous modulation instability (MI) in optical fiber using an incoherent seed with power at the 10(-6) level relative to the pump. We sweep the seed wavelength across the MI gain band, and observe significant enhancement of MI bandwidth and improvement in the signal-to-noise ratio as the seed coincides with the MI gain peak. We also vary the seed bandwidth and find a reduced effect on the MI spectrum as the seed coherence decreases. Stochastic nonlinear Schrödinger equation simulations of spectral and noise properties are in excellent agreement with experiment.