In gremlins, hairy shoulders are dominant over non-hairy shoulders. Peter the Gremlin, who has very hairy shoulders, was adopted at birth and he is finally reunited with his parents 30 years later. He brought his girlfriend, Gretchen the Gremlin, to the reunion. Gretchen studies genetics in college, and notices that neither of Peter's parents have hairy shoulders. What are Peter's parents genotypes? What are Peter's possible genotypes? Why do you think that Gretchen is concerned?

Peter's parents genotypes: hh and hh

Peter's possible genotypes: HH or Hh

Gretchen's concern: The legitimacy of Peter's parent is doubtful

Explanation:

Assuming hairy shoulders allele is represented by H and non-hairy shoulder allele by h. H is dominant over h, hence, for someone to have a hairy shoulder, he/she must posses one H allele (Hh or HH).

Peter's parents do not have hairy shoulders, hence their genotypes will be hh and hh.

Peter has hairy shoulder, hence, his genotype is either HH or Hh.

Gretchen is concerned because neither of Peter's parents have hairy shoulder. This means neither of the parents have the hairy shoulder allele (H). The concern of Gretchen would be about the source of Peter's hairy shoulder allele. If neither of the supposed parents have the allele, where did he get his allele from?

The legitimacy of Peter's parents is questionable and this is why Gretchen is concerned.