A bilateral descent is also know as a two sided descent. Forty percent of the world's cultures are bilateral descents. Most of these societies are highly mobile, foragers and modern industrial. Although, Americans inherit their father's last name our society is considered to be of bilateral descent. In bilateral societies the focus is on the ego and not the family. When a child (the ego) is born they are equally tied to their mother and father's side of the family. They can inherit from either side of the family. When the ego marries they don't leave their family but gain a new one.
The spouse and his/her family is equal to the ego and his/her family. Thus, the ego becomes the son or daughter of their spouses parents and vice versa. The children of their family would view both their mother and father's side of the family as equal members. The problem with this kind of kinship structure is that it can produce conflicts when members have conflicting issues. The family built around this type of kinship only survives as long as the ego lives. Often times once the ego dies the family breaks apart. The terminology European Americans use to describe the family members is shown below.
There once was a time when American society was of unilineality descent. Unilineality descent occurs when the ego only claim their lineage through either a male or female line. Members of these societies generally claim their descent from one common ancestor who tends to be a mythical figure. They society is clan based with each member of that clan claiming the same heritage. Sixty percent of the world's cultures are of unilineality descent. They are primarily associated with pastoralism, horticulture and agricultural systems.
There are two types of unilineality descent, patrilineal and matrilineal.
PatrilinealPatrilineal occurs when the ego belongs only to his or her father's lineage. A male's name, titles and inheritance is given through his father's line. The father's line is passed down from father to son. The males of these societies dominate with power, position and property. Boys are cherished in these societies because they pass on their father's heritage. They are raised to continue their father's line while girls are raised to produce sons for other families. Although, a women marries into a family she does not lose her family heritage even though she is associated with her husband's family. The men value the women of their society because they understand without them their line cannot continue. Thus, the patrilineal society may place stricter regulations and customs on their female members than the males. A woman's conduct reflects upon her father's family and anything she does that goes against their wishes may be punishable by the law. Forty-four percent of unilineality cultures in the world are patrilineal with most of these societies found in the Middle East, East and South Asia. The Shawnee of the United States were a patrilineal society. Here is a chart of family terms and relationships related to the ego of someone who lives in a patrilineal society.
Matrilineal descent is the opposite of patrilineal descent in that the ego belongs to his or her mother's lineage. The mother's names, titles and inheritance is passed down to her daughter. The women dominate these societies with power, position and property. For example, among the Cherokee the men who sat on the council were chosen by the women. If the women did not agree to the way the man was conducting themselves on the council they would have the man removed and replaced with another. Navajo wives can divorce their husbands but if they do the only thing the husband has a right to is the shirt off his back. Most of these societies are dying out because of commercialism.
Ambilineal descent occurs when both the parent's families are recognized and the ego must chose to affiliate with either his/her mother or father's side of their family. Each generation must make the decision as to which part of the they belong to. The decision made by the ego is not taken lightly. It is based on the importance and/or wealth one parent has over the other. The ambilineal kinship system is rare.