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? 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 > Date: Thu, 17 May 2012 00:32:22 -0400 > From: jholl0829@bellsouth.net > To: roots@rootsweb.com > Subject: [ROOTS-L] best DNA test/company > > I am considering ordering a DNA test to help me with my family research. > I am also interested in finding out health information. I saw that > 23forme has a test, however their site doesn't clarify if they are doing > an autosomal test. It would appear from recent posts that most are > agreed that is the best for genealogy testing. I am interested in the > best bang for my buck like most people. I also am not interested in > repeating this if my subscription runs out. > > I am feeling quite naive about all of this. Can anyone help me sort this > out. It would appear the 23forme or the ftdna sites are the better ones. > Does FTDNA provide health information as well? > > Thanks so much, > Jean Holley > ===== > If you would prefer digest mode to mail mode, drop a note to roots-admin@rootsweb.com and ask for the digest... > > ------------------------------- > To unsubscribe from the list, please send an email to ROOTS-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message

here are more official websites... from a from a friend on the genealogy-dna mailing list.. Wikipedia is good but not really official. Here's some alternative, not-so-good but more official sources: http://ghr.nlm.nih.gov/handbook/basics/howmanychromosomes http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Chromosomes.html http://www.genomebc.ca/education/articles/chromsome-fundamentals/ 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