Why do PCR primers (forward and reverse primers) have to be of equimolar concentration?

Hi. You don't have to use equimolar concentrations. But for most types of PCRs it makes more sense. If you have an asymmetric PCR (i.e. one primer at a higher concentration) then there will be preferential amplification of one particular strand of the template molecule. Sometimes you want this, sometimes you don't; depends on the ay. Make sense?