Henry puts his longevity down to "sugar, salt, and beer", while Tim's wife Pauline thinks it's probably the competitive streak that runs strong, with each too stubborn to be the first to die.
The three grew up on the remote Awapika Station about an hour west of Gisborne.
Mrs Mossman said the trio all have a very sharp sense of humour.
She said they had worked hard to carve out a sense of being individuals.
Henry's son David said there were a lot of pranks between the three.
Tim said one of the strongest memories of the early part of his life was serving in World War II. Henry rates being in the Navy, and meeting a wife, who also served in the Navy with whom he had four sons, as a highlight.
At their birthday the three brothers were awarded life membership of the Dilworth Old Boys Association.