Figuring Out Your Ancestry.

You know, I was telling my cousin yesterday. If you want to figure how much DNA you share with a relative, there's a simple technique. I figured it out once. Just count backwards in a straight line. And divide in half with each relative you reach.

Your parents give you half of your DNA. They get half from their parents, so you get one quarter from them. They pass half on to your parents siblings, that's one-eighth. And your parents' siblings are your cousins, so that's one-sixteenth. Notice it's easy to do, if you just follow one straight line.

Actually you don't necessarily have exact percentages past on to you from your parents' parents, etc. Your parents always give you half. But what percentage is actually evenly-divided from the grandparents is up in the air. In HS biology class they explained when the body makes sperm or ova, it shuffles the deck and divides it in half (with the DNA of course). But you never know. For example, you always get half from each parent. But if one parent is half Italian and Irish (this is getting complicate, so bear with me). And the other is half/half the same, your DNA will probably be evenly divided. But you never know. You could be 50% Irish and 50% Italian. Or you might be 49%/51%. Or even 45%/55%. Again you never know. Or one parent could pass none of their ethnic ancestry on to you. But that is very unlikely, you realize. See how percentages work in this?