Okla. Stat. tit. 84, § 84-221: Collateral degrees, how reckoned

In the collateral line the degrees are counted by generations,

from one of the relations up to the common ancestor, and from the

common ancestor to the other relations. In such computation the

decedent is excluded, the relative included, and the ancestor

counted but once. Thus brothers are related in the second degree,

uncle and nephew in the third degree, cousins german in the fourth

degree, and so on. R.L. 1910, Sec. 8426.