Everyone has trouble talking about sex with their kids. I don't care how cool or hip or how with it you think you are - you are still going to have trouble talking to your kids about sex.
Even God had trouble talking about sex. Seriously. If you read between the lines in the story of the Garden of Eden - you see how uncomfortable God was in talking about sex.
Start from the beginning. God made Adam in his image but with one major difference - God was smart whereas Adam didn't know any better because he did not eat from the tree of knowledge - yet. Think about that for a minute. You have a dumb male - a naked male at that - in perfect health just bopping around the Garden of Eden with really nothing to do. Every guy knows what that means.
Adam must have spent all of his time playing with himself.
There must of been a first time when Adam discovered the hard-on. It was probably morning - a BEMHO (basic early morning hard-on) - not to be confused with a HOFNAR (hard-on for no apparent reason). Can't you picture it? Adam, "Hey what's this?" And of course the first thing he does is to touch it. "Hey it feels pretty good to rub this thing. Hey - this - is - great! Now I know how I'm going to spend my day."
As an aside - God gave Adam the job of naming all the plants and animals. So you know Adam must have also named his newly found best friend. That's why men give their penis a name to this very day. It's a throwback to the Garden of Eden. (I call mine Mr. Happy.)
Now God used to roam the Garden of Eden in those days and you know he must have walked into Adam when Adam was jerking it. God, "Whoa - Adam? What are you doing?" Adam, "Just rubbing myself God. Hey watch what happens when I go really fast." God, "Adam that's fine. That's something you do in private." Adam, "Private? What's that? I'm the only one here. I'm in private everywhere I go." God, "I really have to do something about this guy."
So that night God took one of Adam's ribs and created woe-man and the Bible tells us that is was so that Adam would not be "lonely" but really it was because God was probably tired of seeing Adam playing with himself all the time.