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Lost Tribes of Israel

Build a Family Tree Build a Family Tree

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Build a Family Tree (Men Only)
by Marti Louw

The Y chromosome is the keeper of family history on the male side. Written in the letters of DNA, it carries a record of a man's paternal ancestors. Here is your chance to try your hand at being a geneticist and solve a genealogical puzzle using your power of reasoning and understanding of DNA.

When you start the game, you'll find an incomplete family tree of male relatives. We offer simulated DNA sequences from the Y chromosomes of 10 fictitious individuals. These men have a common ancestor and the same last name, but only four of the individuals have been positively identified and placed on the tree. Your job is to complete the rest of the male family tree using DNA information from the Y chromosome.

The Y chromosome is passed from father to son as a nearly exact copy of itself. It is not an identical copy, because during the DNA copying process, small mutations can occur in the genetic code. It is these differences in DNA sequences that allow geneticists to distinguish one individual from another. The more closely related the family tie of two individuals, the more similar their DNA sequences will be, since these mutations accumulate over the generations. A father and son should have the most similar DNA sequences of all.

All the DNA sequences are made up of combinations of the letters A, C, G, and T. These four letters represent the nucleic acids adenine, cytosine, guanine, and thymine, which make up the DNA genetic code.

To figure out relatedness, you'll need to compare the order of letters between the DNA sequences to find the differences, then use your powers of deduction to figure out which individuals are most alike.

Marti Louw is an associate producer at NOVA.

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