It's Pretty Amazing What You Can Learn From A Tube Of Spit

The first thing people think about when they hear "DNA" is blood. Honestly that is what I would have thought about before the popularity of all the genealogy DNA stuff piqued my interest. After doing a little research I was very happy to learn there are no needles involved in the collection of the DNA. I've done two DNA tests with two separate companies to date and one was a cheek swab and the other was a tube full of spit.  It's pretty amazing what you can learn from a tube of spit these days.

Before I go into what I've learned from my tests let me stick a little something from Wikipedia in here to help explain what I'm talking about.

A genealogical DNA test looks at a person's genetic code at specific locations. Results give information about genealogy or personal ancestry. Generally, these tests compare the results of an individual to others from the same lineage or to current and historic ethnic groups. The test results are not meant for medical use. They do not determine specific genetic diseases or disorders.  They are intended only to give genealogical information. 

Types of tests

There are three types of genealogical DNA tests, autosomal (atDNA), mitochondrial DNA (mtDNA), and Y-Chromosome (Y-DNA).  Autosomal tests for all ancestry.  Y-DNA tests a male along his direct paternal line. mtDNA tests a man or woman along their direct maternal line. Any of these tests can be used to some degree for recent genealogy or for ethnic ancestry.

Make sense?  Here's a diagram for those us that are visual learners:

How DNA works. From  http://www.brainpickings.org/index.php/2008/09/29/the-genographic-project/

There are three things to note from this diagram.

1. Genetic material from both parents is passed down to their offspring. (more on this in a minute)
2. mtDNA is passed down from mother to child but never from father to child.
3. Y-DNA is passed from father to sons but not to daughters (girls don't have Y-DNA).  This usually follows a surname.

Genetic Material

Parents pass down genetic material to their children but they don't pass down all of their genetic material. I watched a really good video by Crista Cowan from Ancestry.com that helped explain that concept. She said people believe that a parent will pass down half of their genetic material like in the picture below they would pass down half an orange, half a strawberry, half an apple, etc...  Actually the genetic material is passed down like below where one parent will pass down a strawberry and a watermelon and the other will pass down a lime and a melon. A second child might get an orange and a watermelon from one parent and a lemon and a melon from the other. Two siblings will both get genetic material from the parents but not the exact same genetic material.

From Crista Cowan on Ancestry.com

This is a super crazy basic version of how the genealogical DNA works but hopefully this will help explain things so my future DNA posts will make sense.