  In this work we explore the possibility to fix the number of new
non-sequential chiral-type generations of fermions that could be added to the
standard model by combining the condition that arise from the anomalies
cancellation with the restriction in the number of flavors impose by the QCD
asymptotic freedom. We found that the maximum number of new generations is
four, and that allows us at the same time, to place limits for the electrical
charges of quarks and leptons within an SM-like framework. Our result is
compatible with the constraints involving new generations and their
contributions to the oblique parameters $S$ and $T$.
