Ethan and rose are perfect humans/Superior Virus and infection resistance like albert wesker and jake.

[The Resident Evil]

Yo here is fun fact on re7 and re8,ethan fits all the traits of an immune person like being exposed to a infection or virus ake the moldand it not taking over him and you see him be killed by Jack backer and resurrects with mold powers very similar to when wesker inject himself with proto virus you needed to die to activate its power as a immune human. So ethan is immune aka superior DNA and rose is aswell because we see her die and Miranda resurrects her and guess what she has powers as a baby then.

 

[Teen Tyrant]

You might have something there. While it’s unlikely that two such people would marry, the odds aren't zero, and it would explain a lot. Although, the whole “superior DNA” thing was really only in relation to the Progenitor virus and it’s variants. There’s no evidence to suggest such a thing also applies to other biohazardous substances like Las Plagas or the Mold. If it does, this would mean that Miranda was also such a person, since she bonded with the Mold in the same fashion that Alexia bonded with T-Veronica.