"People with "Norman" surnames like Darcy and Mandeville are still wealthier than the general population 1,000 years after their descendants conquered Britain, according to a study into social progress. Drawing on data culled from official records that go back as far as the Domesday Book as well as university admissions and probate archives, Gregory Clark, a professor of economics at the University of California, has tracked what became of people whose surnames indicated their ancestors had come from either the aristocratic or artisanal classes. By studying the probate records of those with “rich” and “poor” surnames every decade since the 1850s, he found that the extreme differences in accumulated wealth narrowed over time. But the value of the estates left by those belonging to the “rich” surname group, immortalised in the character of Fitzwilliam Darcy, in Jane Austen's Pride and Prejudice, were above the national average by at least 10 per cent. In addition, today the holders of "rich" surnames live three years longer than average. Life expectancy is a strong indicator of socio-economic status."
But not always :
"Throw up your chin a moment, so that I may catch the profile of your face better. Yes, that's the d'Urberville nose and chin—a little debased. Your ancestor was one of the twelve knights who assisted the Lord of Estremavilla in Normandy in his conquest of Glamorganshire. Branches of your family held manors over all this part of England; their names appear in the Pipe Rolls in the time of King Stephen. In the reign of King John one of them was rich enough to give a manor to the Knights Hospitallers; and in Edward the Second's time your forefather Brian was summoned to Westminster to attend the great Council there. You declined a little in Oliver Cromwell's time, but to no serious extent, and in Charles the Second's reign you were made Knights of the Royal Oak for your loyalty. Aye, there have been generations of Sir Johns among you, and if knighthood were hereditary, like a baronetcy, as it practically was in old times, when men were knighted from father to son, you would be Sir John now."
"Ye don't say so!"
"In short," concluded the parson, decisively smacking his leg with his switch, "there's hardly such another family in England."
"Daze my eyes, and isn't there?" said Durbeyfield. "And here have I been knocking about, year after year, from pillar to post, as if I was no more than the commonest feller in the parish…"