Sub-Saharan mtDNA and Y-chromosomes as well as Asian mtDNA (Asian Y-chromosome testing has proven inconclusive at the moment) have been found in significant numbers in the white populations of most areas of the Netherlands and Flanders. This is due to the colonial history of the Netherlands and Belgium. The exception is Friesland, where none has yet been discovered. A study on Belgium outside of Flanders has not yet been performed. We will publish the full results in the next issue.
During the 17th, 18th, and 19th centuries, Africans were present in these regions, with some absorption having taken place over time. Perhaps more significant, though, were the African and Asian wives brought home with Dutch colonists. In the Netherlands, it is not uncommon, for example, to find a sub-Saharan Y-haplotype and Asian mtDNA-lineage in the same phenotypically Caucasian male.
The reason is simple: This person (as do all people) had 256 great-great-great-great-great-great-grandparents. His father's father's father's father's father's father's father's father was black African, and his mother's mother's mother's mother's mother's mother's mother's mother was Asian. But all or most of his other 254 great (x6) grandparents were European. This would leave the male looking utterly European, with his Asian and sub-Saharan DNA being negligible. However, if racial characteristics or ethnic composition were trying to be established by this method, we'd think we were dealing with a half-African half-Asian person, and we'd be completely wrong, since the male is entirely European in phenotype. For this reason, mtDNA and Y-chromosomes cannot be used to determine a person's "race" or appearance. Rather, it can be used to determine some lineages and their possible origins.
Furthermore, no DNA tests to date, including autosomal DNA, mtDNA, and Y-chromosome tests, can conclusively and beyond any shadow of a doubt rule out (or even establish) African or Asian or any other ancestry. Recently, autosomal testing was carried out on a Dutch female who knew she had an African great-great grandparent, and this was corroborated by older family members and memoirs left by grandparents. Yet we could find no trace of it whatsoever. In addition to this, if we say a certain lineage is African or Asian, we don't really know for certain if this is the case. We only know that the lineage in question was found at a relatively high frequency in a certain population that we think is representative of a certain ethnic grouping. We don't, however, know if these people are pure; in fact, they probably aren't, and there is nothing that we can do to establish levels of impurity. Therefore, this is merely a lottery. This isn't to say none of this is useful; it can, as mentioned before, help to determine some lineages.
Dr. Bart Hulsebos
The Anthropology and Genetics Journal
August 8, 2004
This passage was transcribed from a small Dutch journal not available online. The word "significant" should be interpreted cautiously until we have some actual numbers, but it does suggest that Holland and Belgium may have levels of non-Caucasoid admixture comparable to, or even greater than, those of Portugal (which still wouldn't be racially significant). This would come as no surprise since all three countries share similar colonial pasts.