Rebecca Evans created a doc. 1 min Monozygotic Identical Twin Issues: Monozygotes actually share about 6766.2 cM--YOU DO NOT share about 3400 cM, but as of November, 2014, GEDmatch will NOT reflect this in their cM of you as the program was built without taking this into consideration. So, for ALL twins such as sororal (dizygotic sisters), fraternal (dizygotic brothers), unknown types, and monozygotics, you MUST run the One-to-One comparison Tool WITH the Show graphic bar for each Chromosome? checked, or else you CANNOT differentiate whether you are full siblings or DOUBLE SIBLINGS (monozygotics). Rebecca, The graphic will show solid green on all chromosomes for identical twins. The only other case that would show this is if you compared your kit to yourself. Any other comparison will show a mixture of green, yellow, and probably some red. When I compare you and your twin, I see solid green except for a very small handful of isolated yellow and red bars. Those are from sampling errors. It is normal to have a few sampling errors in any test results. The results clearly indicate either identical twins, or the same person who has been sampled from two different testing companies. John Olson Co-Administrator, GEDmatch.Com 2014 November 4 ---- Mr. Olson, Thank you so much for getting back to me and so quickly. So, my understanding is the Total cM feature at the bottom was developed for singletons and will be inaccurate for all monozygotic twins and only shows half of the actual cM shared, so twin siblings should run the one-to-one compare always with the chromosome bars box checked in order to find out that they are not fraternal siblings. Thank you for clearing up the discrepancy! ---- Percentage centiMorgans (FTDNA) Relationship Notes 100% 6766.2 Identical twins (monozygotic twins) Tiny differences between identical twins can now be detected by next generation sequencing. See: Weber-Lehman et al 2014. Finding the needle in the haystack: Differentiating identical twins in paternity testing and forensics by ultra-deep next generation sequencing. Forensic Science International: Genetics; 9: 42-46. See also the editorial by Bruce Budowle in Investigative Genetics: Molecular genetic investigative leads to differentiate monozygotic twins. --isogg.org/wiki/Autosomal_DNA_statistics Fraternal/Sororal twins will show bars like average full siblings: they will be on average 25% GREEN, 50% YELLOW, and 25% Orange-Red. The Green is predicted to be in large chunks. Monozygotics (who are DOUBLE-SIBLINGS) will show bars that are FULLY GREEN on EVERY CHROMOSOME. They will have a handful of minute slivers not green on a few chromosomes that are sampling errors, differences between companies, and the mutations that occur from the twinning event (the act of the embryo splitting--which doesnt happen with sororal/fraternal babies as they had their own embryos from the start). Last Updated 2014, November.
Posted on: Tue, 04 Nov 2014 23:34:40 +0000
Trending Topics
Recently Viewed Topics
© 2015