DNA 101

DNA from Dad Men give their sons a Y chromosome. Since it has no genes from Mom, this DNA can be used to trace paternal history.

DNA 101

_There are three main sources of DNA. Each carries unique information about your family tree. Nuclear DNA (center) Most DNA is in the center of your cells. It is wrapped into 23 pairs of chromosomes, with info from both Mom and Dad. DNA from Mom The DNA in your cells’ mitochondria is exclusively from your mother, so it holds clues to maternal lineage._


_Certain DNA letter sequences can be traced to ancient communities in Africa and elsewhere. A single altered letter in such a sequence is enough to differentiate one group of people from another. This letter is commonly referred to as an ancestry marker. Scientists examine these DNA sequences, comparing the tested person’s ancestry markers to a database containing thousands of others. Letter matches in the markers–for example, the C in the sequence below–can suggest a person’s ancestral geographic origins, which are often suggestive of ethnicity._

Paternal Lineage

_Only men have a Y chromosome, which fathers pass down to their sons. Here, repetitive sequences contain the secrets of paternal heritage. Parts of the Y chromosome contain sequences of letters–such as AGAT–that are repeated two or more times. The number of repeats–not the letters themselves–is distinctive, a clue to paternal heritage. Scientists look for uncommon numbers of repetitions. Two men who share a rare number likely share paternal ancestry as well._