Amatch between the dna in a sample and the genomic dna of a particular individual for a single tandem repeat site is not sufficient to establish identity. however, a mismatch is definitive. the primary reason is that:

The mismatch is definitive, the primary reason is that, the DNA in the sample must match the original genomic DNA.

Explanation:

Tandem repeat takes place only when 'one or more nucleotide pattern is repeated' and it is 'adjacent' to each other. Mismatch indicates that the sample DNA is not the source for that Original DNA. If the sample is the actual source of the original genomic DNA, then it must be matched exactly.

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