What Interact to produce a trait in which neither dominant gene can produce its effect in the presence of the other?

The interaction that leads to a trait where neither dominant gene can express its effect in the presence of the other is known as "codominance." In codominance, both alleles contribute to the phenotype, resulting in a distinct expression that is a combination of both traits. For example, in certain flowers, one allele may produce red petals and another may produce white petals, resulting in flowers with both red and white patches when both alleles are present. This differs from complete dominance, where one allele completely masks the effect of the other.