A more thorough explanation:

Lineal consanguinity refers to the blood relationship between individuals where one is a direct descendant or ascendant of the other. This means that they are related in a direct line, such as between a father, son, and grandson.

For example, if we consider a father, his son, and his grandson, they are related by lineal consanguinity. The father is the direct ascendant of the son, and the son is the direct ascendant of the grandson. Similarly, if we consider a son, his father, and his grandfather, they are related by lineal consanguinity. The son is the direct descendant of the father, and the father is the direct descendant of the grandfather.

Lineal consanguinity can either be downward in a direct descending line or upward in a direct ascending line. In a descending line, the relationship is between a person and their direct descendants, such as a father, son, and grandson. In an ascending line, the relationship is between a person and their direct ascendants, such as a son, father, and grandfather.

Lineal consanguinity is an important concept in genealogy and family law, as it determines the degree of relationship between individuals and can have legal implications in matters such as inheritance and marriage.