This is how it could be done.
Impregnate earth women with sperm that has built in knowledge, say the
knowledge to cure diseases, make computer components, etc..... And
eventually turn on the gene that causes them to remember who and what they
are.
The former would explain how the world has leaped in knowledge from 1900
to
2008 to such a great degree. Sure, there are smart human beings, but ....
Anyways, something to ponder. :)