In which kind of relatives is a genetic disease more likely to occur?

• A. Step relatives
• B. Genetic relatives
• C. Adoptive relatives
• D. Social relatives

Answer: (B)

Genetic diseases are more likely to occur among genetic relatives because these individuals share a significant portion of their DNA. The closer the biological relationship, the higher the chance that relatives may inherit the same genetic predispositions or mutations that can lead to certain diseases. For instance, siblings share about 50% of their genes, while cousins share around 12.5%. This increased genetic relatedness means that if there is a recessive genetic disorder present in one relative, the probability of another relative carrying the same genetic trait is much higher.

In contrast, step relatives, adoptive relatives, and social relatives do not share genetic material in the same way. Step relatives are related through marriage rather than biology, and adoptive relatives do not share genetic backgrounds even though they may share familial bonds. Social relatives are connected through social relationships rather than genetic ties, making the likelihood of genetic diseases occurring among them substantially lower. Thus, genetic relatives are the most significant group when considering the inheritance and prevalence of genetic diseases.