Vampire females can not have children. Only human females can have half vampire / half human children. Both female and male vampires are venomous. There have been very few half breed children, all with a vampire father. Out of the children, the boys have been venomous while the females have not.
Is producing venom sex linked? Why or why not? Draw/describe Punnet Square if possible.
Note: the Mother in this question is assumed to be Human!