The rarity of DNA profiles

TL;DR

This paper explores the statistical rarity of DNA profiles in forensic science, highlighting how dependencies like family or population membership affect the probability of profile matches, which is crucial for interpreting forensic evidence.

Contribution

It provides a deeper analysis of DNA profile matching by considering dependencies such as family and population factors, extending beyond the basic birthday problem analogy.

Findings

DNA profiles are generally rare but can match due to dependencies

Family and population membership influence the probability of profile matches

Dependencies must be considered for accurate forensic interpretation

Abstract

It is now widely accepted that forensic DNA profiles are rare, so it was a surprise to some people that different people represented in offender databases are being found to have the same profile. In the first place this is just an illustration of the birthday problem, but a deeper analysis must take into account dependencies among profiles caused by family or population membership.