**Question:** Sexual intercourse between two persons of blood relations called

A. Homosexuality
B. Incest
C. Extramarital affair
D. Carnal knowledge

**Correct Answer:** B. Incest

**Core Concept:**
Incest refers to sexual intercourse or engaging in sexual activity between relatives who share one or more grandparents. This concept is crucial in understanding the potential risks and ethical implications involved in such relationships.

**Why the Correct Answer is Right:**
Incest occurs when individuals engage in sexual activity who share one or more grandparents. This relationship type is considered incestuous due to the increased risk of genetic disorders and abnormalities that can be transmitted to offspring. Sexual intercourse between relatives increases the likelihood of having children with genetic mutations or abnormalities that would not occur in an unrelated individual.

**Why Each Wrong Option is Incorrect:**
A. Homosexuality refers to sexual attraction and behavior between individuals of the same sex, not related by blood.
B. Carnal knowledge generally refers to sexual intercourse or sexual activity, but it does not specifically point out the relationship status between the individuals involved.
C. Extramarital affair refers to sexual activity with someone outside of a marriage or committed relationship, not related by blood.

**Clinical Pearl / High-Yield Fact:**
Incest is a relevant medical issue when discussing consanguineous marriages, where individuals marry close relatives (e.g., first, second, or third degree relatives). Such unions can lead to an increased risk of offspring with genetic disorders, such as sickle cell anemia, thalassemia, and Tay-Sachs disease, due to the increased frequency of homozygous genotypes (having two copies of the same genetic variant) in offspring from consanguineous marriages.

The potential health implications of incest and consanguineous marriages are crucial for medical professionals, genetic counselors, and healthcare providers to understand when counseling patients and families about reproductive choices.