In a model of hadrons in which the hadron wave function at low ${Q}^{2}$ is represented by a hadron-like Fock state expansion, we calculate the $\ensuremath{\pi}$ and K parton distribution functions by comparing with the experimental data. We show that the model gives an accurate description of available data and, in addition, gives a clear prediction of the initial flavors to be considered at the low ${Q}^{2}$ scale where perturbative evolution starts.