Bankston Family Finder chromosome graph
Your 23rd chromosome is your sex chromosome, either XX or XY. The other 22 chromosomes contain your autosomal DNA. That DNA is assembled "piecemeal" from snippets of your mother's and father's chromosomes. When enough people are tested, the results can be correlated and analyzed to determine which similarities come from which parent, grandparent, and eventually which great-great-great-grandparent. For an example to excite your interest, look at this Geni blog by Ce Ce Moore. (Click here.)
The picture below shows in red (fading to orange or yellow) how one sister compares to the other, and the niece's blue (fading to green) compares to both. Where the blue/green matches the red/orange, all three have identical chromosomal markers. Where blue/green does NOT match red/orange, the niece's DNA matches only one sister.
Another example compares the niece (background) to her two aunts (green & blue) and to a distant cousin (red).
To do: link to Family Finder, to GEDna, picture with another cousin included..
Pages of personal interest: Ron Beatty's home page, Rambo family genealogy, Bankston & Bankson family genealogy, the Camblin family genealogy, the Dorsey Overturff family, cousin Jean's Schenck and Hageman genealogy, Eric's RPM coins, TRS-80 computer & software collection for sale or donation to a museum, Strategy and Tactical Game Collection for sale, many from Avalon Hill.