Incomplete dominance is a type of inheritance pattern in which neither allele is completely dominant over the other, resulting in an intermediate phenotype in heterozygotes. In this case, the black coat color allele and the albino allele do not exhibit complete dominance, as neither allele is able to completely mask the effects of the other.

- **Phenotypes and Alleles:**
- The black coat color is a result of the presence of the dominant allele (B), and the albino coat color is a result of the recessive allele (b).
- When a black-coated mouse (BB) breeds with an albino mouse (bb), all of their offspring have a grey coat phenotype (Bb).

- **Intermediate Phenotype:**
- In incomplete dominance, the heterozygous genotype (Bb) produces a phenotype that is intermediate between the phenotypes of the homozygous genotypes (BB and bb).
- In this case, the grey coat color is an intermediate phenotype between the black and albino coat colors.

- **Blending Inheritance:**
- The concept of incomplete dominance can be understood by considering the idea of blending inheritance.
- In blending inheritance, the traits of the parents are mixed together in the offspring, resulting in an intermediate phenotype.
- In the case of coat color, the black coat color allele and the albino allele blend together to produce the grey coat color in the offspring.

- **Examples of Incomplete Dominance:**
- Other examples of incomplete dominance include red and white snapdragons producing pink snapdragons when crossed.
- In human genetics, an example of incomplete dominance is seen in the inheritance of wavy hair (dominant allele) and straight hair (recessive allele), resulting in individuals with wavy hair having offspring with slightly wavy or straight hair.

- **Conclusion:**
- The gene for coat color in mice appears to be an example of incomplete dominance because the heterozygous genotype (Bb) results in an intermediate phenotype (grey coat color) rather than exhibiting complete dominance of either allele.