Here is a quick and dirty explanation of DNA and Mitochondrial DNA (mtDNA). Imagine in your mind a chicken egg it has a yellow yolk and the clear white viscous albumin surrounding the yolk, and then there is the eggshell. Keep this image in mind for the future discussion. For human cells, the terms will be compared to the chicken egg like this: a) Chicken eggshell = human cell membrane they serve the same purpose in both examples, i.e. the membrane (eggshell) holds the cell together. B) Chicken egg albumin = human cell cytoplasm. C) Chicken egg yolk = human cell nucleus. Here is what happens when a male sperm fertilizes an egg (ovum) from a woman. The fertilized egg at that point will have the male sperm DNA in the nucleus (egg yolk for the chicken egg analogy). The ONLY place in the cell that the fathers DNA can be found is in the nucleus. The Mothers DNA will be in BOTH the nucleus AND the cytoplasm. The DNA in the cytoplasm is a special kind of DNA called Mitochondrial DNA that is ONLY found in the cytoplasm, and it is EXACTLY the same as the Mothers DNA. Thus, Cindys mtDNA is the same as Caseys mtDNA, and the same as Caylees mtDNA. The DNA in the nucleus of any cell from Caylee would be a blend of Casey and the fathers DNA. Mitochondrial DNA is what is being discussed by LE in this case because they obtained the mtDNA profile from the hair in the trunk. They cannot get a full DNA profile from hair because hair cells do not have a nucleus thus they can only look for mtDNA which means they can only determine the female lineage of the specimen being analyzed. Hope that helps.