Board Thread:Naruto Discussions/@comment-30881771-20170330121015/@comment-734582-20170330152332

I wanted to add:

Many clans likely have some weak relation to the Sage. IE by a sage-related clan member marrying to another clan and thus introducing those genes to a new clan (and over time, spreading the genes). For most people it won't matter.

Assuming a human breeding age of around 20, it means that a century has about 5 generations. 50 generations thus went past since the Sage. Assuming Ashura and Indra both had a boy and girl and all their kids have a boy and a girl and never intermarry, we get:

2*2^50 = (Gen1: 4 kids. gen2; 4 kids marry others, get 2 kids each so 8 kids. etc) = 214 million kids.

From this we can derive a few things: (the population of people in the worlds seems to be a few million tops): -intermarriage definitely happened. Though this brings the numbers down a bit, it doesn't change super-radically -Everyone in the Narutoverse has considerable odds of being related to the Sage. -Considering the constant mixing of genes however, many people wouldn't have a noticeable amount of hagoromo DNA. Only inbreeders would have enough DNA left after 50 generations to have noticeable effects - consistent with the Series.

Sidenotes: -the calculation assumes no kids die before their birthing age. Considering both Hashirama's and madara's family though, people had more kids during the Warring States to make up for losses. But people also died much younger, so i think these effects cancel out. The real number to break even is about 2.2 kids per family, but we assumed no inbreeding so a factor of 1 would mean no growth here. -While my model is crude, it gives some simple indications. This includes the fact that 50 generations is a LONG time and that genetic changes from the original population would be massive. Consider that you get 50% of your DNA from either parent. so you have 50% your dad's DNA, your kids have 25% your dad's DNA, your grandkids 12.5, theirs 7.25, etc. After ~7 generations of no inbreeding, your father's DNA is undetectable. In essence my model predicts that no single person would have any Hagoromo DNA. But since those people exist, inbreeding must have happened.

I hope that answers the question more completely.