OK, let’s start from the God Valley Incident. The God Valley Incident took place at an island known as God Valley, 38 years before present time. It consisted of a battle between the Rocks Pirates and a joint effort of the Roger Pirates and the Marines.
For unknown reasons, the world nobles and some of their slaves were present at God Valley during this incident. In order to protect them from Rocks D. Xebec and his crew, who were planning an attack on the nobles, current Marine vice-admiral Monkey D. Garp had to form a temporary alliance with Gol D. Roger, captain of the Roger Pirates.
The God Valley Island has since disappeared without a trace.
We already know that when he was a mere one-year old infant, Shanks was found inside a treasure chest by the Roger Pirates at God Valley. My theory is that most of the Celestial Dragons ran away but one of the families left their child behind. Roger found him …he was Shanks. Roger adopted him as his son.
So now, why I think this theory is right?
- Shanks is 39
- God Valley happened 38 years ago
- Roger told Garp before his execution that a child doesn’t bear the sins of his parents, to convince Garp to take care of his child
- After the fight between the Roger Pirates and the Whitebeard Pirates, Marco told Blackbeard that Shanks and Buggy have been part of the Roger Pirates for many years (they were around 13 years old at that time)
- Roger said in Chapter 966, that it has been a while since he held a baby
Furthermore, I think that one of the things that is very important is the line that one of the Gorosei said – “Because it’s you”.
You wouldn’t let your sworn rival into your “home” even if you respected them a tremendous amount, if not for the fact that they were FAMILY! Which is why Shank’s gets this privelege that no other pirate has.