Inheriting DNA Isn't as Straightforward as You Might Think

DNA is strange. While gene sequencing can give us all kinds of information, constructing a family tree is still complicated. If the number of ancestors we have doubles every generation we go back, pretty soon your ancestors will outnumber the people that were alive at the time. It stands to reason that we are all kin if we go back far enough, so why do we find so many ancestors we aren't related to?

The Tech Interactive tackled a rather common question: "How is it that I know that my great grandmother was married to a Native American, but when I had my ancestry checked, I showed no Native American ancestors?" The simple answer from many internet forums would be that great-grandma fooled around on her husband. But there are other reasons for the disappearance of DNA. The chart above shows how a great-grandfather's DNA (green) might disappear from your profile. That's not likely for all 23 pairs of chromosomes, but it's possible to completely lose an ancestor's DNA as genes recombine over more generations. There are other reasons that have to do with history, and the history of DNA research, which you can read about at The Tech Interactive. -via Damn Interesting

(Image credit: AL Fortier)