Jack's Grandfather is Locke's Real Dad by Fletch

There must be a reason they showed Jack's Grandfather in Season 5 when he gave Jack the shoes that were Christian's. Why introduce a relative of a main character, for no real purpose, that late in the series of the show? My theory is that Cooper was not really Locke's true father, Jack's Grandfather was Locke's real father.

First of all, Locke is easily manipulated. He's the perfect victim for someone like Cooper to con. Cooper does not seem much older than Locke. When Locke's red headed mom gave birth to him, she got pregnant by an older man, which would make this man much older than Locke (at least 25 - 30 years older than Locke). Jack's Grandfather looked to be that age. Plus, it would be fitting that Jack's Grandfather (Locke's dad) supplies the shoes to put on dead Locke's feet. This is something that the Lost writers would do. It turns out that Christian and Locke are brothers, and Locke is Jack's uncle.

There's a ton of "like father-like son" in Lost and it would make sense that if Christian had a "secret" daughter in Claire, then Jack's Grandfather could have a secret brother in John Locke. Plus, wouldn't it be fitting that Jack and Locke were blood related? Another possible theory....what if they are blood related and it takes Jack's blood line to resurrect John Locke?