Answer by Flying ninja. Confidence votes 7. The dominant gene will always cover up the recessive gene, although there are instances of codominance, in which both phenotypes will be displayed, because one gene is not completely dominant over the other.There is also what is called 'incomplete dominance', when the actual phenotype is somewhere between the two.nswer by Flying ninja. Confidence votes 7. The dominant gene will always cover up the recessive gene, although there are instances of codominance, in which both phenotypes will be displayed, because one gene is not completely dominant over the other.