I have to add that the supposed blank slate idea is very very old. Even psychoanalysts do not believe it at all, not the ones current. In fact, modern psychoanalysis uses lots of self-disclosure, lots of give and take, lots of what might seen as a person-centered approach (Rogers).

That's because infant research on attachment and neurology, which started with psychoanalysis, has now more or less proven that the relationship matters more than almost anything else, except random factors.

To believe that a blank slate is useful in an age when it's been scientifically shown to be negative is just ignoring what is going on, what really matters, what science and just good sense tells us.