The only “living” part of hair is the follicle. Once the strand emerges from the skin, it is biochemically inactive and considered “dead.” Hair carries traces of substances from the bloodstream, such as drugs, minerals, and vitamins, but without follicle cells, it cannot identify a specific person, only a group with similar traits. Hair structure is identical in men and women, so gender cannot be determined from hair alone. While nuclear DNA, inherited from both parents, is unique to each person (except identical twins), it is only found in the hair follicle. Shed or cut hair lacks nuclear DNA and cannot be used for individual identification. Therefore, DNA analysis is only possible if the hair has been pulled from the root, not simply cut or broken.
