The DNA fingerprinting technique is based on -

The correct answer is Option (3) → Polymorphism

Option (1) Gene expression — Incorrect. Gene expression is the use of a gene’s information to make an RNA or a protein. DNA fingerprinting studies repetitive DNA that does not code for proteins, so it does not depend on whether genes are expressed.

Option (2) Human Genome Project — Incorrect. The Human Genome Project worked out the whole sequence of human DNA. DNA fingerprinting does not need the whole sequence. It is a quick way to compare only a few repetitive regions of two people’s DNA.

Option (3) Polymorphism — Correct. In repetitive DNA such as VNTRs, the number of repeats differs from person to person. So each person shows his own pattern of DNA bands. That is why DNA fingerprinting is used in crime cases and in paternity testing.

Option (4) Heterochromatin — Incorrect. Heterochromatin is the densely packed, darkly stained and inactive part of chromatin in the nucleus. It is a way DNA is packed, not a difference between two people.

NCERT Extract:
DNA Fingerprinting – …