"direct descent" is correct and usable in written English.
You can use it to talk about a person's relatives, where there is a continuous line of direct relatives going from one generation to the next. For example, you could say: "John is of direct descent from his grandparents, who immigrated to the United States from Ireland."
might have been a relative but hadn't realized that she was of direct descent.
The natural path is direct descent from a parent — from one generation to the next.
Some, like the Lemba of South Africa, claim direct descent from the Jews of the Bible.
Those not stained by direct descent from a racist past distinguish themselves from those that are.
Experts on the royal family say dozens more claim direct descent, though few have been as public with their claims.
Some are "royal highnesses" with direct descent from King Abdul Aziz, while others are "highnesses" from less direct branches.
A phylogeny is a rooted tree that represents the evolutionary relationships of a set of elements (such as species, genes, … ) represented by its nodes: internal nodes are ancestors, leaves are extant elements and edges represent direct descents between parents and children.
(Lugacy, who directed Descent, about a woman's elaborate, extended revenge on a rapist, believes guilt and boredom with our unphysical world both help explain the "torture trend" in movies).
Rather than falling straight down however, the wingless tropical ant glides backwards as it falls, steering itself in a directed descent that lands it on the trunk of the tree; from which it fell saving these insects from reaching the hostile and unfamiliar terrain of the forest floor.
Swaminarayan decreed that the office should be hereditary so that acharyas would maintain a direct line of blood descent from his family.
