.It's also interesting that Italy north and south have different genetics from each other but, Spain is the opposite in which north and south is similar.
This is due to the Reconquista and the repopulation policy. Eache of the conquered areas was occupied by Christians from the north in exchange for farmland and certain privileges. That´s why genetics is similar.
Once in Iberia there are no obstacles to flow between populations, in contrast to the case in Italy, which is an exceedingly mountainous country. Italy can also be accessed more easily by sea from the Aegean and Greece because of those sea and wind currents and because the civilizations to the east were more sophisticated in terms navigation at a much earlier time. ow find it.
Spain is the second most mountainous country in Europe, after Switzerland. It has a totally uneven and complex orography with many reliefs, including its mountainous systems. That orography has influenced the creation of separate societies. However, as I said before, it was the Reconquista and the Repopulation that made genetic similarity possible.