I've heard that the native ethnicity of a population isn't changed all that much if it's conquered by an invading force.

From what I remember, the Visigoths sacked Rome but I don't know if they also went raiding through Italy itself and mixed a bit with the native italians.

There is also the Vandals who might've had the same chance aswell.

The Ostrogoths inhabited Italy after it's fall but just how many actually settled? How big was the Ostrogothic tribe and was it enough to change the gene pool of the native population of Italy?

I've heard that Balesarus on his campaign depopulated the pennisula in his rage and commited mass genocide. Is this true?

I would think that after Rome's fall Italy was a wide open door and any Gauls and Germanics were able to inhabit Italy.

After the Ostrogoths were gone the Lombards moved in and inhabited but did they bring their entire tribe or was it simply warriors that took over? Would they have changed the gene pool enough that the ancient Italians are not the same as the ones we see today?

I've talked with a friend that lives in Italy and he's told me that people in southern Italy look Mediterranean while in the north they look more French. So that makes me think that even through time and conquest the native population ethnicity didn't change all that much.

Though when I look at pictures of ancient Roman statues and see what these people looked like they look different than modern italians to me. I'm not the best at pointing out facial features but they do seem like a different ethnicity.

Since we're on the subject, would this apply to Britain as well? Britain has been conquered and colonized by many different peoples. Would their native ethnicity have been changed as well?