The study you linked is interesting but its results are far from "clear" (see its discussion section but that's probably also just bias and hedging or whatever) and it does have fuck all to do with your proposed thought experiment of a Kaspar-Hauser-like child. Even less so with your confident prediction of how a Kasper-Hauser-like child would turn out. I think you probably know this yourself but these kinds of predictions are something scientists would very, very rarely do - because they know the limitations of their work.
I'm kind of weirded out by this exchange, people here rather confidently express quite a bit of stuff that goes against years and decades of training I received when I became a scientist and I think I'll stop replying now. That was the recommendation of a colleague - who actually is a geneticist - I showed this thread to over coffee as well.
