Passing isn't the same as assimilating, though, if you were passing and your secret was exposed, you would typically lose all privileges associated and you better hope you children are also passing.
I'm not saying it's black and white, but I am saying I don't think most of the people on this forum actually understand how assimilation works in real life. I see a lot of "If they're discriminated against, they would have to change." as if someone from Turkey could change how they look in Germany. Hell, we don't even have to look assimilation in Europe, look at how pervasive the caste system in India remains to this day. Groups can't co mingle unless both are willing, and the tiny trickle of intermarriage that happens on the fringes really isn't worth calculating.