Autosomal DNA test question...?

Question

Recently my dad had an autosomal DNA test done by the website DNAtribes, He is from Germany.. his mom is german and his dad was latvian, however the test came back saying he was most likely to be portugese and northeast polandese... there were also 18 other matches because they tell you your top 20 matches... most of these were north african and mediterreanean... does anyone know or trust DNAtribes reputability? is it possible to breakdown very specific areas and regions that my dad is likely to have in his blood (i.e. lille, france, andalusian spain, asni berber)? oh, in the DNA test there was no mention of him being German at all... he was never told that his mom was adopted or his dad.... but both parents are dead so we cant ask.

please help explain autosomal testing!! serious replies only please.

Answer 1

Hey Valkrygrr...,

I know and trust various DNA testing done. Do not know DNAtribes. I would suggest that you have this person do a comparison test at the free DNA Site also listed below.

The ISOGG organization might be better able to explain the autosomal testing. The last site has the following Definition:

Autosomal STR: STRs are short tandem repeats found in the genetic material (or DNA) that makes up the human genome. Several different STRs, regions that are highly variable in length from individual to individual, have been located and examined. The size of the STR is what scientists look at to help answer questions regarding relatedness. The different sizes of DNA found at these STR regions correspond to, what geneticist call, alleles. These alleles are passed on from parents to offspring. By examining random individuals within a particular population, each allele is found to have a frequency associated with it within that group. It is these frequencies that researchers use to calculate the probabilities of relatedness. GeneTree uses STRs to measure probabilities of paternity, and most other DNA relationship test, including the Y-chromosome Haplotyping.