who would staff the lab?

Why, the saviors of humanity themselves, of course! Toiling diligently to give the new generation a better and brighter future!

And how would they know how to raise those children correctly?

Everybody thinks they know how to raise children correctly. That's why people keep having kids.

A generation raised (successfully!) in a lab would only know how to raise their children... in a lab.

Sometimes the price of freedom is eternal slavery to the lab.