Which statement about sex-linked inheritance is commonly observed in human families?

Which statement about sex-linked inheritance is commonly observed in human families?

• A. Sex-linked traits are more common in females
• B. Sex-linked traits are carried on autosomes
• C. Sex-linked traits are more common in males
• D. Sex-linked traits are inherited only from the mother

Answer: (C)

Sex-linked inheritance involves genes on the X chromosome. In humans, males have one X and one Y, while females have two Xs. If a gene on the X is recessive, males will express that trait with just one copy because there’s no second X to mask it. Females would need two copies of the recessive allele to show the trait, so X-linked recessive conditions appear much more often in males. This is the reason we commonly observe these traits in males in families, with examples like red-green color blindness or hemophilia. These traits are not autosomal and aren’t inherited only from the mother: fathers pass their X chromosome to daughters, but not to sons, while mothers pass Xs to both sons and daughters.

Sex-linked inheritance involves genes on the X chromosome. In humans, males have one X and one Y, while females have two Xs. If a gene on the X is recessive, males will express that trait with just one copy because there’s no second X to mask it. Females would need two copies of the recessive allele to show the trait, so X-linked recessive conditions appear much more often in males. This is the reason we commonly observe these traits in males in families, with examples like red-green color blindness or hemophilia. These traits are not autosomal and aren’t inherited only from the mother: fathers pass their X chromosome to daughters, but not to sons, while mothers pass Xs to both sons and daughters.