The Genome is a Mess

Russell Brandon was not impressed by what 23andme told him about his genome:

Unfortunately, the genome itself is anything but user-friendly. After a decade of research, our data is a jumble of conflicting facts, and no one seems ready to make sense of it. The best metaphor comes from Duke geneticist Misha Angrist, author of Here Is A Human Being and Participant #4 of the Personal Genome Project. "It turns out to be just a total f___ing mess. So instead of having this linear icon representing human biology, the most potent symbol now is the hairball."

In other words, it’s all tangled up in there. Take height, for example. We know that tall parents have tall kids, but if you start looking for specific segments of DNA, you'll find over a thousand, none of which contribute more than a millimeter. The top 180 genetic markers still only account for 10 to 12 percent of the height variation from person to person. The rest of the story refuses to be pinned down. Brilliant people have spent years staring at these numbers, unable to sort them into any kind of rational order, even though to the untrained eye, there seems to be no mystery at all. Tall mom, tall dad: tall kid. But the closer we look, the less we understand.

Right now, as the height example shows, you can learn a lot more about people's genetic heritage by looking at them than by genetic testing.