The crusades were certainly not impact to the overall genome of the region. With limited and temporary success, it was pretty much a failure and certainly didn't change the landscape. Today's archaeologists still use cranial shape and capacity to determine ethnic origins of people. Head shape and capacity never changes never changes in time. It is a benchmark indicator of race and ethnicity. Ancient Israelite remains show they were dolichocephalic and had identical characteristics to northern Europeans today. Jews living in Israel today are not dolichocephalic, but having brachiocephalic cranial head shapes..