During the lifetime of Genseric significant migration of the Vandals took place. Previously the Vandals had migrated from southern Scandinavia to Silesia around 120 BCE. By the third century of the Common Era they had migrated to Pannonia (in present day Hungary) where they were confined by the Goths in the year 330, where Constantine the Great gave them permission to settle.
Cawley states that Genseric was born around the year 400, an illegitimate son of Godegisl, King of the Vandals.  Procopius names “Gizerichus notus” as son of “Godigisclo”.  Wikipedia follows Cawley in rendering the name "Genseric."  Wikipedia also adds that he was also known as Gaiseric or Geiseric (Latin: Gaisericus; reconstructed Vandalic: Gaisarīks), was King of the Vandals and Alans (428–477) who established the Vandal Kingdom and was one of the key players in the troubles of the Western Roman Empire in the 5th century. 
The Dictionary of African Biography refers to him as Geiseric, but notes the name also appears as Gaiseric and Genseric.
The Dictionary of African Biography suggests a birth year of 389, the son of Godagisil, king of the Hasding Vandals, and an unknown concubine. 
His place of birth is unknown but may be assumed to be at the location of the Vandals at the time, which would have been Pannonia, present-day Lake Balaton, Hungary.
In response to raids by the Huns around 400, many Germanic tribes migrated into the territory of the Roman Empire. The Vandals crossed the Rhine into Gaul in the year 406. 
Genseric's father died in battle against the Franks during the Crossing of the Rhine in the year 406. At the time, Wikipedia reports that Genseric became the second most powerful man among the Vandals, after the new king, his half-brother Gunderic. Since a birth year of 400 would make Genseric's age to be 6 at this point, an earlier birth year of 389, making him age 17, would be more credible.
Genseric's brother was Gunderic (379–428), King of Hasding 
In 409 they crossed the Pyrenees into the Iberian Peninsula. The two Vandal groups, the Hasdingi and Silingi, settled in Gallaecia (nortwest Iberia) and Baetica (south-central Iberia) respectively. 
In 418 the Visigoths invaded Iberia. The Iranian Alans and Silingi Vandals subjected themeslves to the rule of Genseric's brother Gunderic, the Hasdingian Vandal ruler, and were pushed from Gallaecia to Baetica by a Roman-Suebi coalition in 419. 
Genseric succeeded his half-brother in 427 as Genseric King of the Vandals.  Isidor's Historia Gothorum, Wandalorum, Sueborum names "Gesericus frater Gunderici" when recording that he succeeded the latter as Vandal king in Spain. 
During his nearly 50 years of rule, he raised a relatively insignificant Germanic tribe to the status of a major Mediterranean power. After he died, they entered a swift decline and eventual collapse.
Cawley reports that the Vandals crossed into North Africa en masse in May 429, although what prompted this move is unclear. The Chronicon of Bishop Idatius records that “Gaisericus Rex…cum Wandalis omnibus” left “Bæticæ Provinciæ litore” and went “ad Mauritaniam et Africam” in May 429. 
Wikipedia reports that, succeeding his brother Gunderic at a time when the Vandals were settled in Baetica, Roman Hispania (modern Andalusia, Spain), Genseric successfully defended himself against a Suebian attack and transported all his people, around 80,000, to Northern Africa in 428. 
Wikipedia adds that he might have been invited by the Roman governor Bonifacius, who wished to use the military strength of the Vandals in his struggle against the imperial government.
According to Iordanes, the Romans lost the province of Africa to the Vandals "per Bonifatium", although this does not explain why they arrived there in the first place. The exploits in Africa of "Geiserici ducis" are described in detail in the Victoris Vitensis Historia. 
Genseric conquered Hipona in 429, and Carthage in 439, where they established their capital. The Vandal nobles rebelled against their leader in 442. 
In 430 Genseric turned on Bonifacius, Roman Governor of North Africa. Genseric caused great devastation as he moved eastward from the Strait of Gibraltar across Africa. He turned on Bonifacius, defeated his army in 430, and then crushed the joint forces of the Eastern and Western empires that had been sent against him. 
In 435 Genseric concluded a treaty with the Romans under which the Vandals retained Mauretania and part of Numidia as foederati (allies under special treaty) of Rome. 
"In a surprise move on October 19, 439, Genseric captured Carthage, striking a devastating blow at imperial power. Added to his own burgeoning fleet, the Kingdom of the Vandals now threatened the Empire for mastery of the western Mediterranean Sea. Carthage, meanwhile, became the new Vandal capital and an enemy of Rome for the first time since the Punic Wars."
Seizing Sicily in 440 AD and later the Balearic Islands, Sardinia, Corsica, and Malta, Genseric’s fleet soon came to control much of the western Mediterranean.
In 442 the Vandals were recognized as independent rulers of Byzacena and part of Numidia when they concluded a treaty with Rome. 
He had been promised the daughter of Roman Emperor Valentinian in marriage to his son Huneric, but in 455 Valentinian was murdered and the new emperor took Valentinian's wife as his own and married Valentinian's daughter to his son. Genseric avenged this insult a month later, possibly at the request of Valentinian's widow, with his invasion of Rome itself.
Subsequently, the King defeated two major efforts by the Romans to overthrow him, that of the emperor Majorian in 460 and that led by Basiliscus at the Battle of Cape Bon in 468. 
King Genseric made an agreement with Odoacer King of Italy about Sicily, the latter retaining control over the island in return for yearly tribute. 
The Eastern Roman Empire's first expedition against the Vandals in Africa in 468, led by Basiliscus, brother-in-law of Emperor Leo I, failed despite numerical superiority. 
The Vandal kingdom dominated the western Mediterranean, with Corsica and Sardinia. 
Cawley notes that the Victoris Tonnennensis Epsicopi Chronicon records the death in 464 of "Gensericum Wandalorum rex" after reigning for 40 years. 
Upon his death, he was succeeded by his son Huneric.
Cawley shows Genseric as the father of three children: Huneric, Theodoric and Gento.
Have you taken a DNA test? If so, login to add it. If not, see our friends at Ancestry DNA.