Part egg plant? 
Sicilians are part eggplant/neegul ancestors?The character who is trying to rile up his Italian-American assailant by implying his ancestors were "n***ers" and that he is "part eggplant"? Well, you may be surprised to find that his reading is somewhat tendentious.
The specific historical event that the character alludes to is the Arab conquest of Sicily in the 9th century. Arabs from North Africa ruled the island for over a century and a half, before they were ousted by the Byzantine emperor's Norman mercenaries. However, his statements rely on two extremely racist and easily falsifiable assumptions: first, that the Sicilian population before the arrival of the Arabs was of Northern European extraction, with light hair and blue eyes; and second, that the Arab invaders were black Africans.
In reality, the population of Sicily - like that of all Mediterranean peoples - is of mixed ancestry. Inhabited since prehistoric times by Sikels and Sikanians of unknown origin, the island was settled from the 8th century BC onwards by Phoenicians and Carthaginians (originally from the Eastern Mediterranean) and by Greeks. The constant wars and resettlement processes of the ensuing centuries not only mixed these populations together, but also added mercenaries of numerous ehtnicities to the gene pool. Eventually conquered by Rome, the island became part of a vast empire within which minorities from all regions mingled in search of social and economic opportunities, with Sicily being central to the seaborne trade networks of the Roman Empire. By the time of the Arab conquest, the general population of Sicily would have been indistinguishable from that of the rest of Southern Italy, Spain, Greece, and the North African coast. It is very likely that there would also already have been black Africans moving about for well over a millennium.
The people who invaded the island in the 9th century, meanwhile, were typically identified as Arabs, but probably included many North Africans of various ethnicities. They may have included some sub-Saharan Africans too, but on the whole they might not have looked so different from the Sicilian population itself.
Genetically, the real change came when the Normans (i.e. Viking mercenaries) invaded in the mid-11th century and proceeded to conquer the island. These mercenaries were the first Northern Europeans to settle the island in meaningful numbers, and since they continued to rule Sicily for several centuries, it is generally thought that the occasional appearance of blonde hair and blue eyes on Sicilians is down to their influence on the gene pool.