Final answer:
Two unaffected parents producing an affected child is indicative of autosomal recessive inheritance. This situation occurs when both parents are carriers of a recessive allele and the child inherits both recessive alleles.
Step-by-step explanation:
When two unaffected parents produce an affected child, this is characteristic of a recessive pattern of inheritance, specifically autosomal recessive inheritance. This means that the trait in question is located on one of the autosomes (non-sex chromosomes) and requires two copies of the recessive allele for the trait to be expressed. Both parents must be carriers of the recessive allele, each contributing one to the offspring resulting in the affected child. A common example is the inheritance of albinism. If both parents have one normal allele and one recessive allele for albinism, they appear normal but can have a child with albinism if the child receives the recessive allele from both parents.