Band: The visual image on an autoradiograph that represents a particular DNA fragment.

Bandshift: The phenomena in which identical DNA fragments will move through an electrophoresis gel at different rates because of contamination or alterations to the DNA itself. This phenomena is usually observed in forensic samples that are partially degraded.

Bases: (In DNA) Four building blocks of nucleic acids. They are Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). They are complementary in that the only stable base pairs are AT/TA and GC/CG. The length of DNA fragments is measured in base pairs (bp).

Base Pair(ing): The complementary partnership of A with T and G with C that brings the two opposite strands of a DNA molecule together to form the double helix.

Bayes' Theorem (as applicable to parentage testing): A statistical procedure to assess the relative probability of two alternative possibilities based on acquired information.

	W =	(CPI) (Pr)
		(CPI) (Pr) + (1 - Pr)

W =	Probability of Paternity
CPI =	Combined Paternity Index
Pr =	Prior Probability

Best Interest of the Child: The legal standard or doctrine for making child-related decisions.

Biological Father: The man who provided the paternal genetic material of a child.

Blot: See Southern blot.

Burden of Proof: The party asserting a claim must prove such claim is true. In paternity cases, the burden in most states requires that paternity be established by a "preponderance of the evidence," meaning that paternity (or lack of paternity) is "more likely than not." We call this the 50.01% test, meaning that if evidence is even slightly greater than 50-50, it constitutes a "preponderance of evidence." Some states insist on a higher standard, known as the "clear and convincing evidence" test. This test is more stringent (harder to overcome) than the "preponderance" test, but not as strict as the "beyond a reasonable doubt" test, the standard in criminal cases. Many states have thresholds of 95% or more percent in order to create a presumption of paternity.