Which statement best describes a limitation of hair analysis for individual identification?

Which statement best describes a limitation of hair analysis for individual identification?

• A. Hair shaft morphology is unique and can identify a person with high certainty.
• B. DNA from the hair follicle can yield usable profiles when follicular tissue is present.
• C. Hair analysis cannot provide any physical characteristics.
• D. DNA from the hair shaft alone is always sufficient for identification.

Answer: (B)

Hair DNA analysis hinges on obtaining nuclear DNA from cells in the hair follicle, not from the shaft itself. The follicle contains nucleated cells, which can provide a full, individual-specific DNA profile, while the hair shaft often lacks enough nuclear DNA for reliable identification. Therefore, a usable profile depends on follicular tissue being present; without it, the analysis may be inconclusive or fail. This reality highlights the limitation: identification is not guaranteed from hair unless the follicle is available. While mitochondrial DNA from the shaft can sometimes be analyzed, it is less discriminatory and cannot uniquely identify most individuals, reinforcing why the presence of follicular tissue is crucial for a robust ID. The other statements misstate the science—hair shaft morphology is not unique to individuals, some physical characteristics can be inferred from hair, and DNA from the shaft alone is not always sufficient.