FWIW, your original no-call rate seems substantially higher than I'm accustomed to seeing. For example: An M kit: 0.15566093841309 percent. An A kit: 0.06391337857398 percent. The fact that you previously said several thousand no-call RSIDs were the same for both companies gives rise to a wild speculation in my mind, viz is it possible that you are a chimera? This is the "vanishing twin" scenario, where the fertilized eggs that would ordinarily give rise to fraternal twins fuse early in development. This could affect the base-calling algorithm, which expects a double-strength signal for homozygous results and a single strength signal for each allele in heterozygous results. If you were a chimera, you might see an extra strong signal for an allele carried by both of the original twins, while the heterozygous signal would be weaker and perhaps rejected by the base-calling algorithm. Ann Turner On Wed, Jan 6, 2016 at 12:02 PM, David Schroeder via < genealogy-dna@rootsweb.com> wrote: > Error Rates (No-Calls): > Original Ancestry: 1.9444416327699 percent Fixed Ancestry: > 0.99817658890539 percent > Original 23andme: 2.1583132550279 percent Fixed 23andme: > 1.482448214704 percent >