By E. H. McKenzie | Updated Aug 30, 2022
DNA testing has its roots in the late 19th‑century work of Gregor Mendel, who studied inherited traits in pea plants. Mendel’s experiments laid the groundwork for discovering DNA—the molecular blueprint of life. While 99% of human DNA is shared, the remaining 1% provides enough unique markers to identify an individual with remarkable precision.
DNA is composed of four nucleotides—adenine, guanine, cytosine, and thymine—that pair to form a double‑helix. Each human cell contains 46 chromosomes, half inherited from each parent. This chromosomal arrangement allows scientists to trace genetic lineage and determine ancestry.
In 1856, Mendel cross‑bred pea plants, documenting dominant and recessive traits. Although rudimentary, these tests revealed the mechanisms of heredity and earned him the title “Father of Genetics.”
DNA evidence entered U.S. courts in 1987 when a match between a suspect’s blood and semen at a crime scene secured a conviction. Conversely, DNA proved its value in exonerations, such as Glen Woodall’s 1991 release after a four‑year wrongful imprisonment.
Because DNA is inherited from both parents, it can conclusively establish parentage. A landmark 1998 study used descendants’ DNA to confirm that Thomas Jefferson fathered all six of Sally Hemings’ children.
Military programs began collecting DNA samples in 1992 to identify fallen soldiers. In 1998, DNA recovered from a bone helped identify the Unknown Vietnam War service member buried at Arlington National Cemetery as Air Force 1st Lt. Michael Blassie.
