youre wrong beautiful beast
it is a bloodlimit, its just not EVERYONE recieves bloodlimits, the 1st hokage was the only one known to possess wood jutsu and it was a blood limit, the mangas state that itself.
His brother didnt obtain it because it simply wasnt in his genetics
Not every uchiha gets the sharingan, only strong uchiha do.
It even said "yamato was injected with the 1st DNA"
That is a bloodlimit, a genetic (DNA) jutsu.