Final answer:
Collateral relatives are identified differently depending on the kinship system and the sex of the connecting relative. In a bilateral descent system, EGO is closely related to same-sex siblings of their parents, while in a bifurcate merging kinship system, these relations merge into the immediate family and opposite-sex siblings are separated into a different category.
Step-by-step explanation:
The practice of identifying collateral relatives relies on understanding the type of kinship system in place. In a bilateral descent system where kinship is traced through both the mother's and father's lines, siblings of the same sex as a connecting relative, such as EGO's parents, are likely to be considered more intimately related to EGO, akin to additional parents (e.g., mother's sisters are also called 'mother'). Conversely, in a bifurcate merging kinship such as the Iroquois system, these same-sex siblings and their children (parallel cousins) are merged into the immediate family unit, while opposite-sex siblings of EGO's parents (and their offspring, or cross cousins) are bifurcated or separated into a distinct category of relationship.
For example, EGO's relationship with his mother's brother's children would be different from his father's brother's children; the former would be simply 'cousins,' whereas the latter would be regarded as 'siblings' under a bifurcate merging system. Such distinctions can influence social interactions and marriage practices, as parallel cousins are often treated as siblings and thus typically not considered as marriage partners, while cross cousins may be preferred as they merge children back into the primary kinship line, maintaining the kindred's stability across generations.