In this hypothetical paternity case, four autoradiographs show DNA "fingerprints" taken from three individuals: a mother, her child, and the child's alleged father. Each autoradiograph compares equivalent DNA segments from the three individuals. The two dark bands in each column represent one individual's DNA segments -- one inherited from that individual's biological mother and the other from the biological father. These segments differ in length from person to person; for this reason they are used as genetic markers. Here, each length is designated by a letter, A through O. The two letters associated with each segment indicate the individual's genotype.

Instructions
1. Under each column in the autoradiograph, write the letters associated with each individual's genotype. For example, the genotype of the mother in the first column is A/D. Then, circle the letter in the child's genotype that represents the gene inherited from the mother.
2. Which "letters" must the child have inherited from its father?
3. Based on this information, what evidence suggests that the alleged father could be biologically related to the child?

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Earth and Life Sciences Program Contents

The Long View
Seeing and Believing
In-Depth Investigation: The Dating Game