Yukawa textures and anomalies

We augment the Minimal Supersymmetric Standard Model with a gauged family-dependent U(1) to reproduce Yukawa textures compatible with experiment. In the simplest model with one extra chiral electroweak singlet field, acceptable textures require this U(1) to be anomalous. The cancellation of its anomalies by a generic Green-Schwarz mechanism requires sin2θw = 38 at the string scale, suggesting a supersting a superstring origin for the standard model.