Identification: monozygotic twins: practice question

A Forensic Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Forensic Medicine · Identification: monozygotic twins

Sample item

Two identical twin brothers are suspected of a robbery. A blood stain at the scene gives a nuclear STR profile that matches both. Which feature can still separate them?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Their fingerprint patterns

Monozygotic twins arise from one zygote and share the same nuclear DNA, ABO group, mitochondrial DNA and Y haplotype. Fingerprint ridge patterns are shaped by the intrauterine environment as well as by genes, so they differ even between identical twins.

Option by option

  • A. Their fingerprint patterns (correct)

    Correct. Fingerprints differ between identical twins.

  • B. Their Y-chromosome STR haplotypes

    Identical twins share the same Y chromosome haplotype.

  • C. Their mitochondrial DNA sequences

    Identical twins share the same mitochondrial DNA from the mother.

  • D. Their ABO blood groups

    Identical twins share the same ABO blood group.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More Forensic Medicine questions

Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is A, Their fingerprint patterns. Monozygotic twins arise from one zygote and share the same nuclear DNA, ABO group, mitochondrial DNA and Y haplotype.

Why is "Their Y-chromosome STR haplotypes" not the answer?

Identical twins share the same Y chromosome haplotype.

Why is "Their mitochondrial DNA sequences" not the answer?

Identical twins share the same mitochondrial DNA from the mother.

Why is "Their ABO blood groups" not the answer?

Identical twins share the same ABO blood group.

What concept does this question test?

It tests Identification: monozygotic twins in Forensic Medicine. Fingerprint ridge patterns are shaped by the intrauterine environment as well as by genes, so they differ even between identical twins.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Identification: monozygotic twins?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.