For those of you looking for more evidence of my son's genius status: William recently learned to sign the word "light". This sign involves reaching upward towards the light in question and opening and enclosing your hand.
Unlike previous signs, which may have been random gestures or flukes, even my husband, ever the doubting Adam, has admitted that this appeared to be a genuine sign. It seems clear that William is on the road to becoming the first infant University graduate.