Explanation: We will use the Punnett square to find the phenotype.  D d   D DD Dd  d Dd dd From the table formed we can see that there are 3 'D' alleles and so 75% of offspring will have the dominant phenotype out of a total 100%. DD, Dd, Dd shows Dominant phenotype. Hence, the percentage of offspring which will have the dominant phenotype when Dd and dd individuals mate is 75%.