Dating or engaging in romantic relationships with certain relatives is considered taboo or socially unacceptable in many cultures, while relationships with others may be more accepted. The degree of acceptability varies across societies, and the reasons behind these perceptions can be complex, involving cultural, psychological, and biological factors. Here are some distinctions and potential reasons:
Sibling: Dating a sibling (brother or sister) is typically universally considered taboo and is illegal in most places. The reason behind this is largely based on the need to prevent genetic problems that can arise from close relatives having offspring. Inbreeding (reproduction between close blood relatives) increases the risk of inherited genetic disorders because it amplifies the chance of sharing harmful recessive genes.
Cousin: Dating or marrying a cousin is more acceptable in some cultures than dating a sibling, but it is still seen as taboo in others. The degree of cousin relationships seen as acceptable can vary based on cultural, religious, and legal factors. Some societies allow first-cousin marriages, while others discourage or prohibit them. From a genetic standpoint, the risk of genetic disorders from first-cousin relationships is lower than that of sibling relationships but still higher than unrelated couples.
Step-relative: Dating a step-relative, such as a step-sibling or step-cousin, is generally considered more acceptable because there is no direct genetic relationship between the individuals. They are related only through marriage and not by blood, which removes the concerns about genetic issues.
Psychological reasoning: The aversion to romantic relationships between close relatives, especially siblings, is rooted in several psychological factors:
Westermarck effect: The Westermarck effect is a psychological phenomenon observed in many societies, where individuals who live in close proximity during early childhood tend to develop a natural aversion to sexual attraction later in life. This is believed to be an evolutionary adaptation that helps prevent inbreeding and maintain genetic diversity within a population.
Incest taboo: The incest taboo is a cultural norm that prohibits sexual relationships or marriages between close blood relatives. It is a widespread societal rule found in most human cultures and can be enforced through various means, including legal restrictions and social stigmatization.
Family dynamics and socialization: The family unit plays a significant role in shaping social norms and values. In most families and societies, sibling relationships are nurtured as non-romantic and platonic, making the idea of romantic involvement with a sibling psychologically uncomfortable and socially unacceptable.
Overall, the perceived taboo and disgust associated with certain relative relationships are a combination of biological concerns (genetic risks) and cultural norms developed to promote healthy and diverse societies. These norms have been shaped over time to protect against potential genetic harm and maintain the stability of social structures.