Matching the Tsunami Baby DNA

Well, it’s getting to that time of year when my Bio Sci Fi students encounter biology more bizarre than science fiction. We already saw the new trachea engineered from stem cells, and the glow-in-the-dark cat that will help find a cure for AIDS. This week we get to the basics of DNA mapping.

So here’s a problem. Let’s suppose that a tsunami devastates a coastal city, and afterward a baby gets rescued.  We use DNA testing to match the baby to one of three pairs of parents (1, 2, 3). Here are the results of the DNA test:

(A) Explain how the DNA data shown are obtained.

(B) Explain which pair of parents belong to the baby; say how you know.