"In order to... it is necessary."

To be a woman, your parents need to put in a good effort during... :O

So, if everyone were diligent, humanity would have gone extinct long ago (only girls would be born) :cool:

You need beer and a couple of horny teenagers.

To have beer and be one of those horny teenagers, you need your parents to not put in effort again. But this time, at the stage of upbringing.