Colour blindness and Haemophilia are examples of what type of genetic conditions?

• A. Autosomal recessive conditions
• B. Mitochondrial inheritance
• C. Sex linked conditions
• D. Polygenic traits

Answer: (D)

Colour blindness and haemophilia are inherited through genes on the X chromosome and show a sex‑linked recessive pattern. Because the responsible genes are on the X, males have only one copy; a single mutant allele on that X will express the condition, so these traits appear more often in males. Females have two X chromosomes, so a single mutant allele usually doesn’t cause the disease unless a second copy is also mutated; such females are typically carriers who can pass the allele to their offspring. This pattern gives the characteristic family pedigrees where affected males are common, and affected females are rare. It isn’t a mitochondrial (maternally inherited) pattern, nor an autosomal recessive or polygenic trait, which is why those options don’t fit.