Apartheid in medieval England?

There is an interesting article in the New Scientist magazine here about the impact of a small group of Anglo-Saxon invaders on the genetic makeup of central England. The setup:

Genetic analysis of men in modern-day central England shows that more than half of them possess a Y-chromosome that can be traced to Germania - an ancient region of central Europe.

Historians argue that fewer than 200,000 Anglo-Saxons invaded the population of about 2 million Celtic Britons during the 5th century. All things being equal, this number should account for just 10% of the gene pool being Anglo-Saxon.

They then go on to claim that:

In an attempt to explain this anomaly, Mark Thomas at University College London, UK, and colleagues came up with a theory that an apartheid social structure benefited the people - and therefore the genes - of the Anglo-Saxon race at the expense of the native Celtic genes.

Evidence of the apartheid system can be found in ancient texts such as the 7th century laws of Ine, Thomas says, which place a greater value on the life of an Anglo-Saxon. For example, these laws stated that if an Anglo-Saxon was killed, the "blood money", or "Wergild", payable to the family was up to five times more than the fine payable for the life of a native Celt.

In societies where one race is socially and economically favoured over another - like the Anglo-Saxons were over the Celts - the dominant race is likely to have more children and these children are more likely to survive to a healthy adulthood. Rather than interbreeding with the native population, the invading Germanic tribes actually out-bred them, Thomas believes.

To my simple mind, it seems that "to the victor go the spoils" - in this case, the fair Celtic women of the time. I sincerely doubt that the Anglo-Saxons brought enough women to England at the time to breed with - they must have taken the hometown girls for wives, resulting in the Y-DNA results quoted in the article.

Apartheid? I doubt it. Ravishing and pillaging - probably. Works every time. Easy, eh? But we are much more civilized and sophisticated now, aren't we? Our esteemed scientists seem to want to apply 21st century social norms to 6th century realities.