Final answer:
Parallel cousins and cross cousins are terms used in kinship systems to differentiate between the relationships individuals have with their cousins through their parents' same-sex siblings or opposite-sex siblings.
Step-by-step explanation:
Parallel cousins and cross cousins are terms used in kinship systems to differentiate between the relationships individuals have with their cousins through their parents' same-sex siblings or opposite-sex siblings. In the bifurcate merging kinship system, parallel cousins are the offspring of EGO's parents' same-sex siblings, while cross cousins are the children of EGO's parents' opposite-sex siblings.
For example, if EGO's father has brothers, then their children are EGO's parallel cousins. On the other hand, if EGO's mother has sisters, then their children are EGO's cross cousins. In many tribal societies, individuals often choose their marriage partners from among their cross cousins, which helps maintain a stable and significant presence of the kinship line across generations.