Final answer:
Bilateral descent is a system where an individual traces kinship through both parents' ancestral lines, which is common in modernized nations like the United States. Unilateral descent, in contrast, follows one parent's line only and can be patrilineal, matrilineal, or ambilineal. Bilateral descent incorporates both maternal and paternal relatives into one's family circle.
Step-by-step explanation:
Bilateral descent refers to the system of tracing an individual's kinship through both the mother's and the father's ancestral lines. This means that relatives on both sides of the family are considered as part of one's kinship circle. In contrast, unilateral descent traces lineage exclusively through one parent's line—this can be either patrilineal (father's line), matrilineal (mother's line), or ambilineal (mother's or father's line depending on the situation). A person who traces kinship through their father’s line only would be practicing a form of unilateral descent, specifically patrilineal descent.
In societies with bilateral descent, like the United States, individuals inherit and carry on cultural and familial traditions from both parents. This approach has become predominant in many modernized nations, blending the families and creating a diverse family tree. Utilizing bilateral descent can affect many aspects of family life, including surnames, inheritance, and familial responsibilities.