(1) Lineal consanguinity is that which subsists between two persons, one of whom is descended in a direct line from the other, as between a man and his father, grandfather and great-grandfather, and so upwards in the direct ascending line; or between a man andhis son, grandson, great-grandson and so downwards in the direct descending line.
(2) Every generation constitutes a degree, either ascending or descending.
(3) A person's father is related to him in the first degree, and so likewise is his son; his grandfather and grandson in the second degree; his great-grandfather and great-grandson in the third degree, and so on.
Legal Commentary & Landmark Judgments: Section 25
Section 25 defines lineal consanguinity as the relationship subsisting between persons where one is descended in a direct line from the other, whether ascending (ancestors) or descending (descendants).
It operates in two opposite directions: lineal ascent, which connects an individual upwards to their father, mother, grandfather, grandmother, and remoter ancestors; and lineal descent, which connects an individual downwards to their son, daughter, grandson, granddaughter, and remoter descendants.
Under sub-section (2), every generation in lineal consanguinity constitutes a single degree of relationship. Thus, a father and son are related in the first degree, a grandfather and grandson in the second degree, and a great-grandfather and great-grandson in the third degree. This generational counting provides the mathematical basis for determining inheritance priority.
Section 25's definition of lineal consanguinity governs the distribution of the two-thirds residue under Section 33. Lineal descendants take preference over all collateral relatives (such as brothers, sisters, uncles, or cousins). If any lineal descendant exists—even a great-grandchild—the entire collateral line of kindred is completely excluded from intestate inheritance.