How do kids turn into vampires on sims 2 double deluxe?

You cannot turn a child into a vampire if they are human, however, If a vampire and a human sim have a child then the child will be part-vampire. They will not be able to drink other sims, and will not get vampiric moodlets, but they will look like a vampire, complete homework quickly, and gain skill points quickly. Part vampire sim children also enjoy drinking plasma juice.