Jakob theory

I don't think Jakob and Dom are biological siblings but half-siblings, why?

I believe Dom and Mia's Mother gave birth to a Child when she was having some sort of an affair with Kenny Linder (He looks to similar to Jakob.) I believe that somehow Kenny Wanted to Kill or get rid of Dom and Mia's Father and that's why he supposedly "kills" Mr. Toretto on the stock car race circuit. That also maybe why their mother is never mentioned and why Dom couldn't outrun his past (Beat Jakob's father with the wrench almost killing him.) I don't know if it is a valuable theory, but man both John Cena and that guy that was shown to Brian some pictures from, he was all beaten up, but he as similar face traces with Cena so that's what I think it's going to happen.

https://postimg.cc/tscPQsjq

That also explains why both Dom and Jakob don't have the same type of blood. Dom has more of that "Latino" traces/heritage just like Mia. But Jakob has more traces of a Typical American guy just like a Jock or something.