Many of the characters in Boromir's immediate family appear nowhere outside The History of Middle-earth, and apart from his father Boron and his son Bregor, this genealogy is provisional. Boromir's daughter Andreth is the subject of a lengthy, though non-canonical, account of her own. See her entry in the Excyclopedia for more information.
We have no dates of any kind for Boromir, but if we assume that the birthdates of the Men of the House of Bëor followed a fairly regular pattern, then he would have been born in roughly the year I 350 (that is, some forty years after his grandfather Bëor arrived in Beleriand). It is not known how long he lived, but assuming a typical lifespan of around seventy years, he would have died in approximately the year I 420.