"Intelligent" Design?

For the past few years there's been a progressive effort to apply religious teachings to what is often called the real world. There's a strong ongoing debate concerning the teaching of intelligent design in public schools or "balancing" it with evolution.
Personally I've always believe that the 'evolution' of humankind was a combination of God's creationism and the natural evolution of the species. God did indeed create the first beings but man himself evolved from that original creation. This , in my opinion is the only realistic and logical explanation.
Otherwise what you have is something I'd have a difficult time reconciling.
Lets look at what the theory of 'intelligent design' is at it's core.

Genesis ii, 21-22
So the Lord God caused a deep sleep to fall upon the man, and while he slept he took one of his ribs and closed up its place with flesh; and the rib which the Lord God had taken from the man he made into a woman and brought her to the man.

That's one rib, one woman, right?

Okay lets move forward, Adam and Eve have done the deed. We have Cain and Able. Able it would appear is a hard working, decent sort a guy, who loves his God, and builds a lovely alter to honor him. Cain on the other hand, is at best not as talented at alter building as his brother. When Cain sees how impressed God is with his sibling, he gets all pissed off and kills his brother in a fit of rage. Now, that's murder, right? Yet does God banish Cain from the family compound? Does he have Daddy Adam lock Cain up 'for life' or worse give him the 'death' sentence for his crime? He does not. But that's a topic for another day.
Moving on, along comes Seth. Which makes Seth and Cain, literally the 'fathers' of the human race.
Now, here's my question. Where's the Mother?
Were there daughters born (of Adam and Eve) that are not mentioned?
The problem here is no matter whether there were daughters we don't know about, or worse there were no daughters and Eve remained the only woman, what you have is NOT a pretty picture.
THIS is the problem with Intelligent Design. If you are going to teach the 'theory' of man being created by God, then you are going to have to teach our children that the human race has it's roots founded in incest. Because in order for Seth and Cain (that brother killer) to have children they had to have to had sexual relations with their [previously unmentioned] sister/sisters, or their Mother.
Do we really want to teach our children that the very roots of our race are a murderer and incestuous brothers and their Mother and or sisters?
The 'theory' of evolution is starting to look a whole lot more attractive and simple. Don't ya think?

[editors note: This post was inspired by a post found at Adgitadiaries.]