Actually Congress has done that on more than one occasion. The 1953 legislation was retroactive to children born between 1941 and 1952. Link.
You are pathetically wrong on this one.
Yeah right.
Ah, NO, you are even more wrong.
Congress can grant “Citizenship” retroactively.
Congress can NOT grant “Natural Born Citizenship” retroactively.
It is not logically or Constitutionally possible.
Only some of them. However, the law made those persons citizens, but I think you'll not find "natural born" anywhere in that law.