The primary source which records his parentage is not known.
He succeeded his father in [915] as IOANNES II Duke of Naples. The Chronicon Ducum…Neapolis records that "Ioannes" succeeded Duke Gregorius (without specifying the relationship between the two) "7 tertia ind" and ruled 4 years, 7 months and 12 days.
The name and origin of Duke Ioannes's wife is not known. There is a possibility that she was the cousin of Ioannes.... [One] interpretation of a charter issued by her grandson, Duke Ioannes III, dated 18 Jul [949], is that "domini Marini lociservatoris…visavio vestro" who is named in the document (the relationship referring to the issuer of the charter) was the duke´s great-grandfather, either through his mother or his grandmother who are not otherwise known. This hypothesis, as it relates to the paternal grandmother of Duke Ioannes III, would also explain the reintroduction of the name Marinus, given to her son, into the main line of the ducal family. 1
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