tag:blogger.com,1999:blog-37148773.post6871340190893625352..comments2024-03-27T14:50:47.345-04:00Comments on <center>Sandwalk</center>: What happens when twins get their DNA tested?Larry Moranhttp://www.blogger.com/profile/05756598746605455848noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-37148773.post-78596146006126087512019-01-25T18:52:25.519-05:002019-01-25T18:52:25.519-05:00I design microarrays for a living. Yes, the data i...I design microarrays for a living. Yes, the data isn't going to be 100% the same on each run, even if you start with the same tube of DNA extract. (Our spec is 98% reproducibility; a good run is 99.8%, a solid run 99.6%, and below that we get twitchy.) Keep in mind that there's a lengthy process between DNA and data, such that you're just not going to get usable data for every single spot on the array on every single run. It's more often "No Call" than actually wrong, because we have many layers of checks for bad data, but still.<br /><br />So, the data isn't going to be the same every time. If there's a quality difference, that can easily be enough to punt a DNA region from "Eastern European" to "Broadly European". Between companies, you'll also have differences in the ancestry databases they use, and in the algorithms they use to determine what is a match.<br /><br />There are scam artists who will basically collect your sample and fake a report. But these companies are all legit, and the data is as consistent as the technology can manage.Anonymoushttps://www.blogger.com/profile/13286978767391370468noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-19626008954563905382019-01-24T20:54:09.177-05:002019-01-24T20:54:09.177-05:00You could get your own DNA tested again and see if...You could get your own DNA tested again and see if your results agree with your prior results.whimplehttps://www.blogger.com/profile/15979048635836472956noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-37120994703048094032019-01-24T12:01:51.218-05:002019-01-24T12:01:51.218-05:00X - chromosome inactivation wouldn't change th...X - chromosome inactivation wouldn't change the presence of the DNA, just the expression of the genes on the chromosome.nbuckleyhttps://www.blogger.com/profile/02303451170889338172noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-22168050970336333742019-01-24T11:17:58.856-05:002019-01-24T11:17:58.856-05:00When I started to read your article, I thought any...When I started to read your article, I thought any differences in identical twin sisters would be a result of X-chromosome inactivation. When you didn't mention that, I wondered if X-chromosome inactivation happens before a zygote twins. Would you elaborate on the timing of these events and if X-chromosome inactivation would affect genetic ancestry testing more or less than somatic mutations?<br />Anonymoushttps://www.blogger.com/profile/01491313292239906929noreply@blogger.com