So, there's two brothers...one with his same mother, and one with his same father.
Unless Nate is outright lying, and not merely spinning to "help" out John, I think we could rule out Nate as being the one John could have referred to. The other option is that John made it up about there being any brother he went with to a party at the Ramseys.
BTW, it has been stated by those with knowledge that these "brothers" weren't on the party guest list, that everyone at the party was someone close to the Ramseys, and that everyone there knew who everybody else was. It has also been stated that there's no evidence a brother of John ever worked for John Ramsey.
FReeper bonfire brought up the thought that could they have been working at the party in some capacity, not guests, and the thought was, working in connection to the party, NOT working in construction. I've not seen any other speculation on this.
Until this is explained by facts of the case being exhaustively pursued and such crucial ?? answered, I'm just in a "wait and see" mode.
>>>So, there's two brothers...one with his same mother, and one with his same father.>>>
The brother that he shares the same mother with, also shares the same father.
In other words. Mother & Father have older brother and John. Mother and father divorce and father remarries and has Nate.