Dear Newsgroup: I appears that we are once again 'blessed' with another trip through scientific la-la land in order for Zelda to 'appear' to be our DNA 'genius'. Her response is total crap and it is too bad she didn't stick around for any real explanation for the situation she was attempting to respond to while appearing to actually know what she was talking about. The reason for the match as described in the questioners message is that different parents (and differnt generation) are involved. Naturally, the chromosome sites that are tested, (though they are tested on the SAME SITES for son, father and cousin) the cousin will show a MUCH larger difference than will the son to his own father. The son has 50% of the father's genes afterall (50% of the mother's genes as well - half from one and half from the other). The 4TH cousin once removed genes has been diluted by the fact that his parents, and his parents' parents and so on back 6 generations common ancestor with the cousin's parents differing each time through the generations... each parental pair donating their set of genes to HIS mix. Naturally, that 21756 SNP block, for instance, is going to be broken up into many, many smaller and smaller chunks, each individual 'smaller chunk' being donated from one of these generational parental pairs, but not necessarily from the common ancestor because that individual smaller chunk may come from the partner that is not related to the common ancestor. [ Sorry for the long sentance, but it is the nature of the beast. ] Therefore the cousin does not have the large chunk, but only parts - and not necessarily the SAME parts as from the common ancestor (because that part may not have come from the common ancestors line, but from the non-related partner in each generation). This has nothing to do with whatever Zelda was attempting to talk about, because frankly, what she said was gobbly-gook, intersperced with DNA nomenclature to give her response some basis for you to believe what she is telling you. I try to avoid that when possible. It is sad, but it causes more damage than good. Half-identity?? Fortuitously stitched-together composite of shorter genuine matches"??? What, Zelda, is a genuine match versus a non-genuine match? "The father has two chromosome 15's, and it could be that one matches his son while the other matches his cousin" Are you kidding me??? And you are giving people DNA advice??? The matched pairs of each chromosomes (other than the X-Y SEX" chromosome) that you constantly refer to are MATCHED, they are pairs, they come from THEMSELVES during cell division - during mitosis! Thus the term matched pairs! (I can throw around DNA terms as well and it should not add to my statement because I simply know the definition/usage of a word ) DNA genealogy is a complex and YOUNG science. All the bugs have not yet been worked out and some of the probabilities given by the testing sites are given to help the lay person understand what the degree of a matched relationship might be. These probabilities are guidelines, not fast hard facts. The nature of DNA testing for genealogical purposes is NOT smoke in mirrors like many of these people would like you to believe. It is based upon scientific fact. The problem you have is to determine who is giving you facts to help you and who is giving you garbage to help themselves. There are many sources of information available to you, but NEWSGROUPS is apparently NOT one of them yet, because of this current situation of giving out bad and inaccurate information; quoting people on irrelevant topics (but still concerning DNA) and claiming them to be doctors - for whatever that means. Doctors of what is what I ask myself and what is their expertise on genealogical DNA testing. And then, there is the fact that we can all claim to be doctors on the internet, can't we? Just like we can all claim to be DNA experts, that is, until we are de-bunked. As Zelda had done, and I have done in the past - seek out REPUTABLE sites or sources for your information. They are out there - some are even here and why they remain silent when they see this crap going on is beyond me. Zelda's email I am responding to is below Actually trying to help- Dave Michaelson ================================= Message: 3 Date: Fri, 18 May 2012 20:58:47 -0500 From: Nelda Percival <nelda_percival@hotmail.com> Subject: [ROOTS-L] Autosomal chromosome pairs see website To: <roots@rootsweb.com> Message-ID: <COL116-W251AA1EAAE74A54E3EFCB0E41F0@phx.gbl> Content-Type: text/plain; charset="iso-8859-1" For information in the chromosome pairs : see: Dear Nelda, You could just refer him to something basic like http://en.wikipedia.org/wiki/Human_chromosomes. It shows the fact that the autosomal chromosomes come in pairs in a diagram at the top of the web page. Sincerely, Tim Janzen TIM JANZEN IS A Doctor Here is an email that was on the Genealogy-DNA mailing list about pairs.... She wrote: > The father matches the son on chromosome 15 from 18,334,687 to 100,278,685 > 118 cm and 21756 SNPs. The father matches a 4th cousin once removed by the > same surname on chromosome 15 from 31,109,924 to 85,833,111, 62 cm and 14018 > SNPs. > > Given that the areas on chromosome 15 overlap entirely, and it is a large > segment, how can the cousin not show as a match to the son? ZELDA's RESPONSE: Bear in mind that a "match" is actually not an identity, but rather a half-identity. The father has two chromosome 15's, and it could be that one matches his son while the other matches his cousin. It is certainly curious that the matching segments overlap completely, but I'm guessing that there are lots of other matching segments, too, and this one just happens to be the most striking case. Also, don't forget that the matching is not a rigorous comparison of phased chromosomes, but rather a test for half-identity or better on successive diploid loci. The apparent long matching segment with the cousin might turn out to be a fortuitously stitched-together composite of shorter genuine matches Nelda L. Percival, Administrator of Y-DNA surname projects Gilpin, Cupp, Bonstein and Gillock My Genealogy - http://freepages.folklore.rootsweb.ancestry com/~bonsteinandgilpin/index.htm GeneticGenealogy - http://www.geneticsand.us Blog - http://aircastles-lets-talk.blogspot.com/ GilpinGenetics: http://www.gilpingenetics.us/ Web Mistress for LCRG - http://www.rootsweb.ancestry.com/~molcgdrg