"Theodore said that young witches were the most valuable for the spells. It was preferable that they were used before their tenth birthday. After that, they apparently get too close to puberty to be nearly as effective. Wizards can be used if no witches are available, but the magic is more powerful with girls. He wished to surpass me in the Dark Lord's eyes and favor by offering up his three granddaughters for the privilege of sustaining his life."