Wassup guys.

I have this pain of a math problem that I need help with. There's this question:

"Suppose that the probability of a parent having no offspring is 1/4, and the probability of the parent having two offspring is 3/4. What's the probability that the population will die out in the 4th generation?"

The lecturer insists that there are no errors in the question, grammatical or otherwise.

Help anyone?