I have a bit of confusion.
The rinnagan- It originated from one man. It has huge potential, so much nagato could not use it to its full potential because. He couldnt even do jutsus at the level the sage of the six paths did. This proven when pain use Chibaku Tensei. But Nagato was a strong opponent, wasn't he?
And as of resent chapter releases its can be assumed that it is the first Doujutsu as well? That then leaded to its modern cousin the sharingan, and thus it is a genetic trait? It was the eyes of the sage Madara called it.
Senjutsu- A secret that was only, as far as we know, taught by frogs/toads, and only with the help of special oil. it has the side effect that When the user cant balance their chakra out they then turn in to a frog. It increases the over all power of person using it in just about every way though. Madara has stated that Senjutsu also originated from the sage of the six paths.
Two very powerful things from one man.
The confusing part lies with in that the rinnagan in a genetic trait and senjutsu is something to be learned but, the issue mainly how its learned. The sage of the six paths gave his body and eyes to his disciple, one each. which caused all that is now to be as it is. The sage started all this basically, if he hadnt existed then life would be completly differnt. his disciple with the body of the sage ( Senjutsu ) doesnt pass it on genetically, you had to be taught it. it is odd became it has some relation to frogs. very few people show a chance of using it. While the disciple with the eyes of the sage ( rinnagan ) had an ability that was genetically passed to others. And ever instance of any doujutsu it doesnt take training to activate, people just develop in to the ability.
Why is senjutsu not genetic? And with the connection to frogs does that mean the sage of the six paths had an affinity for frogs? I doubt it. Then why are frogs mixed in with senjutsu? Personally I think Kishi tried to add some flair to it with the whole turning in to a frog thing, it should have been just been as another jutsu is, and taught as basic like controlling your own chakra is. with out the "Oh no im turning to a frog". and if the Rinnagan in genetic and is the predecessor to the sharingan. Does that imply that there was a clan for the Rinnagan?
What am I trying to get at?
WHATS WITH THE DAMN FROGS?
No I am not a frog hater Kermit is cool....