So, this got me thinking:
Tobirama, the inventor of shadow clone jutsu was never mentioned to have spouse or child of his own, meanwhile his brother Hashirama is famously known to have wife and granddaughter (Tsunade). Mind you, Tobirama lived longer than Hashirama, he become 2nd hokage after his brother the 1st hokage died.
Is there any chance the reason Tobirama didn't continuing his legacy is because he's addicted to this method of selfcest?