So, I was a huge fan of the theory that we are different because of additional Cro Magnon genes. It seemed plausible; it would have made for a big enough difference.
Then I read this book on fetal development, and partially changed my mind. To summarize, the book says that a "Memory Block" develops in the fetal brain that causes it to forget things it learns, i.e. "the uterine wall is hot". As such, it would touch the wall of the uterus several times, thus developing reflexes. In some cases, when the mother's health/the strength of her immune system falls below a certain level, this memory block fails to develop, and so for instance the fetus learns that the wall of the uterus is hot, and does not touch it again, never developing those reflexes.
That would at least explain a lot. So much for learning "disorder".
Then I read this book on fetal development, and partially changed my mind. To summarize, the book says that a "Memory Block" develops in the fetal brain that causes it to forget things it learns, i.e. "the uterine wall is hot". As such, it would touch the wall of the uterus several times, thus developing reflexes. In some cases, when the mother's health/the strength of her immune system falls below a certain level, this memory block fails to develop, and so for instance the fetus learns that the wall of the uterus is hot, and does not touch it again, never developing those reflexes.
That would at least explain a lot. So much for learning "disorder".