If both parents have the genotype Aa Bb Cc Dd, their phenotype is determined by the dominant alleles for these four traits. If we observe on trait, we have 3 times bigger possibility for a dominant (AA, Aa, and Aa) than recessive phenotype (aa). Since we observe four different traits, the probability for an ofring to look like their parents is (3)/(4)*(3)/(4)*(3)/(4)*(3)/(4)=0,32. The number of possible phenotypes is 2 for each of the 4 traits (for example Aa and aa for the first trait), which makes it 16 (2 2 2 * 2).