Diahan Southard, noted genetic genealogy educator and author, has created a YouTube video called "DNA Isn't Fair." Here's a description of her video:

DNA inheritance isn’t fair — and understanding who actually makes it into your DNA (and who doesn’t) is the foundation of effective genetic genealogy. This simple concept adds needed context to your DNA testing experience. Once you understand how inheritance really works, your entire research strategy becomes clearer.

In this short video, you’ll see:

• Why you don’t inherit DNA from all of your ancestors — even recent ones

• Why some kinds of great-grandparents contribute zero DNA to you

• How DNA inheritance principles effect which cousins you share DNA with

Understanding DNA inheritance will subtly influence the way you interpret your ethnicity results, your cousin matches, and your DNA research plan.

View her excellent, nine-minute presentation here.