Final answer:
Consanguinity refers to the marital practice of marrying someone who is closely related by blood, such as a cousin.
Step-by-step explanation:
The marital practice followed by Martha and Daniel's families, where they are in love with their first cousin, is known as consanguinity. Consanguinity refers to the practice of marrying someone who is closely related by blood, such as a cousin. It is important to note that while consanguinity is accepted in some cultures, it is generally discouraged or prohibited in many societies due to concerns about genetic risks and societal norms.