Final answer:
Determining the percentages of ancestral DNA sequences provides an estimate of a person's genetic ancestry through molecular analysis and comparison with sequence databases. This practice aids in various applications including forensics and understanding migration patterns, but the results are estimates and must be interpreted cautiously.
Step-by-step explanation:
Using DNA to determine the percentages of sequences from different ancestral groups results in an estimate of one's genetic makeup. This practice is commonly referred to as DNA ancestry testing or genetic genealogy. Molecular analysis utilizes the comparison of DNA sequences to establish genetic relationships and lineage. This method can help indicate the percentages of one's ancestry that comes from various regions or populations.
By sequencing the DNA from an individual and then comparing it to sequence databases, such as GenBank, scientists can estimate the person's ancestry. However, the estimates are just that—estimates, and they should be understood within the context of potential limitations such as convergent evolution or genetic homoplasy, where unrelated DNA sequences appear similar.