Paternity test results have life-altering implications. These quantitative calculations are the bases for long-term financial obligations and lifelong familial associations. Despite their grave significance, most people do not comprehend the fundamentals of this modern scientific marvel.

A Matter of Basic Biology

If a child has a certain gene that its mother does not, then that gene had to have come from its father. If a man tested as being the suspected father does not have this gene, there is no possibility of his having fathered the child. Thus, he will be “excluded” in competent paternity test results.

Chromosomes are internal cellular structures that contain genes. Essentially, genes are enzymes that govern physical characteristics like hair color and height. Except for sperm and eggs, all normal human cells contain 46 chromosomes. Each parent contributes 23 of this total 46-chromosome complement.

Human chromosomes contain thousands of genes. Paternity tests compare only enough of these genes to accurately assess the probability of a biological relationship between two parties. The specific genes selected for comparison are easily identifiable due to their prominent chromosomal placements.

Sheer random chance dictates that many people with no biological relation whatsoever will share one or more common genes. For instance, billions of people share the gene that causes five fingers to form upon a normal human hand. Other genes, however, are much more specific to individuals.

Paternity test results are calculated by comparing a tiny subset of genes that are very rarely shared by unrelated parties. As the number of commonalities identified within this genetic subset increases, the effect of random chance decreases.

Thus, the more individual-specific genes shared by a child and putative father, the greater probability of their biological relationship. This makes it possible to calculate the likelihood of a man’s fatherhood to a certainty of 99.5 percent or greater by comparing just 10 to 15 genes.

Blood Thicker Than Water

The nuclei of red blood cells contain genetic data identical to all other human cells. Blood is also easy to collect and handle. Thus, blood sample collection is a common means of obtaining the necessary genetic material to conduct and calculate paternity test results.