What is the fact of Molecular Biology on which DNA fingerprint is based?
The DNA fingerprint, the method of individual identification using DNA, is based on the fact that the DNA of every individual (with exception of identical twins and individual clones) contains nucleotide sequences exclusive to each individual.
Even though normal individuals of the same species have the same genes in their chromosomes, each individual has different alleles and even in the inactive portions of the chromosomes (heterochromatin) there are differences in nucleotide sequences among individuals.