What trait is characterized by a gene where all moths have the trait if the father possesses it?

• A. Hypertrichosis
• B. Color blindness
• C. Muscular dystrophy
• D. Down syndrome

Answer: (A)

The trait characterized by a gene where all moths exhibit the trait if the father possesses it indicates a pattern of inheritance known as paternal inheritance, which is typically seen with traits linked to the Y chromosome. Hypertrichosis, also known as "werewolf syndrome," is a condition that is often inherited in an X-linked manner, but certain forms can be autosomal dominant. However, in the context of the question, it specifically suggests that if the male parent has the trait, all offspring will express it, aligning with traits that follow direct paternal transmission.

This can reflect a scenario where the gene responsible for the trait is located in a region where expression is dependent on the presence of the father’s alleles, leading to all offspring inheriting the trait directly from him if his genotype includes the associated alleles. Genetic traits like color blindness, muscular dystrophy, and Down syndrome follow different patterns of inheritance that do not strictly adhere to this paternal transmission dynamic, mainly involving X-linked or complex patterns of inheritance that do not guarantee expression in all offspring based solely on the father's characteristics.