Explaining to kids where babies come from - 70's style

If you are unsure about what to say when your children ask you where babies come from ... try the 70s style "tell it like it is" comic series that is currently doing the rounds as a viral email. The images (I believe) were taken from a popular book published in the 70s which parents could use to explain the facts of life to their children. I haven't seen any recent books that are trying to do the same but surely the original work is a land mark in publishing and education!
Have a look:

But wait ... it gets better ... (if you are offended by explicit comic sex ... don't click on "read more")

Explaining the facts of life

Our eldest son has reached the age where he is curious about how babies are created. Enter the perennial problem; how to explain sex to a child. I chose the straightforward approach, reasoning that if I explained sex in a matter-of-fact way then he would quickly grow bored and move on to another topic of discussion. It went something like this: “Well, it’s just like the animals you see mating on nature programs. The male puts some sperm inside the female to fertilize her egg and that makes a seed which grows into a baby. How was school today? Which classes do you like the best? What would you like for supper?” He replied with a question I wasn’t expecting: “How come you still do it when you don’t want any more babies?”