Haku Adopting his Nephews

Hi Scott,

After watching Hobbs & Shaw's third act on Samoa, I started thinking about the different wrestling lines from Samoa and Tonga, which of course brings up Haku and his three boys in NJPW.  I know that Loa is his biological son, while Tama and Hikuleo are his biological nephews that he then adopted.  I was doing some research online and didn't see anywhere the story as to how/why this badass warrior that would rip eyes out in bar fights ended up adopting these kids, showing that he also has a heart of gold.

How did Haku end up becoming the best wrestling dad of his generation, and what happened to Tama and Hikuleo's birth parents?

Dammit I still need to see that movie.  Plus John Wick 3.  Stupid kid cramping my style.  Well at least we can take her to Marvel movies.
Anyway, I can only assume Haku murdered the rest of his family in a wacky bar fight and adopted the children so that he could raise them to be his army of Tongan warriors.  Or car detailing crew.  Either way.