I believe the other commenter was saying that at the time people believed it was an acceptable answer, just as now you're saying it's a plausible explanation for this problem.
Yes, I understood he was referencing "at the time", that's why I included the word _was_. My point still stands. Although many people did accept it, it WAS not an acceptable answer, and IS still not an acceptable answer to justify segregation.
So wait, do you reject the possibility that this situation couldn't be the exact same as the one in the past? It seems like you're saying, "Yes, genetics was not an acceptable answer then, but it is now."
If that is what you're saying, then what makes it different now?