Metal Gear Solid V The Phantom Pain - Ishmael Theory

Just my option Kojima Loves to use religious references with the sons after all
The dates later on suggest that he would at least look old enough to be Ishmael in the game...
As an extra to add to this Solidus has strong ties to Ocelot who he was in coverts with at least from the Shadow Moses incident & possibly well before then... (Helping him hide from the Patriots after the incident)