A cross of a white horse(WW) and a red horse (RR) produces all Roan (RW) offspring. This type of inheritance is called: Incomplete dominance.
Incomplete dominance:
Incomplete dominance occurs when one or both alleles of a gene are only partially expressed at a particular location. A different or intermediate phenotype is typically produced by this kind of gene interaction. In the case of incomplete dominance, the variations (alleles) are expressed in a reduced ratio rather than as dominant or recessive.
An allele is a type, variety, or group of gene expressions. A creature is made up of one gene and two alleles, one from each parent. A dominant allele is one that suppresses or conceals other alleles while firmly establishing itself in the offspring. An allele is considered recessive if its effects are suppressed by the dominant allele and do not show up in the progeny. The multiple alleles (two or more) for a single gene are referred to as "many alleles."
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