Which type of inherited traits can have a codominant or incompletely dominant relationship

Co-dominant: in which both the alleles show their effects. Incomplete dominance: phenotype show intermediate of both alleles, no one is completely dominant on each other.

Explanation:

Co-dominance: when both alleles in the genotype are seen in the phenotype, means they both show their effect when they are in heterozygous condition.

Example: AB blood group

In AB blood group both alleles show their effect:

The IA and IB alleles are co-dominant.

Incomplete dominance : it is a mixture of two alleles, in which the phenotype is the mixture of both the alleles.

For example, a mixture of blue and red flower, produce a purple flower.