Chapter 23: Evaluation of the Strength of Forensic DNA Profiling Results

 Mendelian Genetics  Mendel’s First Principle- segregation of alleles  Mendel’s Second Principle- independent assortment  Meiosis- gametes formed ▪  Diploid: 22 pairs of autosomes and 2 sex chromosomes (XX & XY) Forensic Biology by Richard Li2

 Inheritance of genes measured using probabilities  Population Genetics: Studies the causes of the observed patterns of genetic variation  Allele Frequency  Genotype Frequency Forensic Biology by Richard Li3

 Hardy-Weinberg Principle  1900’s  Allows predictions of the genotype frequencies to be made from the allelic frequencies  Conditions: ▪ Population is large ▪ Randomly mating ▪ Absent from mutation, migration, and natural selection Forensic Biology by Richard Li4

 Evaluate the strength of the match  Two approaches:  Profile Probability  Likelihood Ratio Forensic Biology by Richard Li5