In the context of genetic liability, which statement is correct?

The statement indicating that one sex is more likely to develop a condition if a sibling of the opposite sex has it captures an important concept in genetics related to sex differences in disease risk. This phenomenon is often observed in multifactorial conditions, where the presence of a disorder in one sex can influence the likelihood of the other sex developing the same condition, reflecting patterns of genetic liability.

For instance, certain conditions may exhibit a higher incidence in males compared to females (or vice versa), and having a sibling of the opposite sex affected by the condition may increase one's own risk due to potential shared genetic and environmental influences that differ between sexes. This highlights the complex interplay between genetics and sex, where familial patterns can inform genetic counseling and risk assessments.

The other options don't accurately represent the interplay between genetic liability and condition risk. Multi-factorial conditions may not be equally distributed across sexes and often show different prevalence rates. Genetic liability does indeed influence the expression of traits, contradicting the implication that it has no effect. Lastly, the idea that both sexes have the same genetic risk for all conditions is a generalization that overlooks the nuances of sex-linked and sex-influenced traits. Thus, the correct answer underscores a specific aspect of genetic risk that is crucial for understanding