Hello! I have a question. Prior to the Muslim conquest of Spain, the Iberian Peninsula was inhabited by various tribes such as the Germanic Visigoths. Now current Spaniards and Portuguese look usually different from modern Germanics, and I was curious. After the conquest of Spain was there much intermarriage between the Arabs and the Spaniards that may have caused Iberians to look so different?
The Visigoths had little genetic impact on the population of the Iberian Peninsula; during their tenure as rulers of Spain they were overwhelmingly in the minority. The groups that entered Spain in the latter half of the fifth and first half of the sixth centuries likely only numbered in the tens of thousands-- the old estimate of 100,000 is certainly too high. So on the eve of the conquest in 711, we should not expect the population to look like the Goths who entered the peninsula nearly two centuries earlier, much less modern Germans.
Resident populations tend not to be completely uprooted when a new group invades or conquers a territory. Shifts in ethnic identity tend to be rooted in culture, not genetics. The greater part of the population of Muslim Al-Andalus was likely descended from those who had inhabited the peninsula prior to 711. That being said, there does seem to be a significant amount of movement between North Africa and the Iberian Peninsula over the next several centuries-- which in some measure should be expected, as southern Spain was drawn into the larger Islamic world of the western Mediterranean. Early Arab settlement centered on the river valleys of the Guadalquivir and the Ebro and groups of Berbers settled in the Meseta, as well as other frontier zones. Hugh Kennedy notes that unlike conquests in other parts of the Mediterranean, the conquerors did not found garrison cities; settlement and migration was largely unplanned. While some areas saw more Arab settlement than others, large parts of the peninsula were still dominated by the native population, many of who did convert to Islam. This was however, was a slow process, and for the first several centuries, a large part of the population of Al-Andalus remained Christian.
The influence of North African and Middle Eastern peoples in the genetic composition of modern Spain is certainly greater than that of the Visigoths, though I have hunch it is still not as great an influence on the genetic makeup of Spain as one might think. This 2010 study(PDF!) indicates that Spaniards are largely similar in genetic composition to the rest of Northern and Western Europe, though there is evidence of a more diverse haplotypic structure. You may consider cross-posting to a subreddit better equipped to answer questions about genetics and haplogroups.