It seems that the show has now taken to developing the theme that Lex was Born Evil, and some fans are jumping on this with great cries of glee.
I did a search on the internet and found discussions of the topic 'Born Evil'. Some people like the idea, and indeed it does simplify matters a lot. If people are Born Evil and Born Good, then we ourselves -- those of us sitting here thinking about the topic -- are clearly in the latter group, right? And that means we are immune to the danger of ever Turning Evil ourselves, and that means that whatever we do will never be evil, because only evil people do evil, and evil people were Born Evil, and we are not among that host.
Notice how this protects Clark from the charge of being evil, no matter how bad his actions might be? Clark clearly was not Born Evil, so whatever he does -- mindwiping friends, burning down buildings and so on -- is not truly evil, and all he has to do is feel a little sad about it all, and everything's fine and he's a Hero again.
Lex was Born Evil, according to the show now. Tess said so. All Luthors should be killed at birth, she says, because they're Born Evil, and the show seems to be supporting her by showing Little Lex turning evil before our eyes. And the fans are wetting themselves with glee.
Now, let us consider this theory more considerately than it deserves, just out of fairness. If Lex was indeed Born Evil, that should mean evil is in his DNA. Right? Like, someone is born blond because it's in their DNA. If I don't have blond genes in my DNA, my hair is NOT going to be blond, unless I bleach it. I have blond genes somewhere in my DNA, but because blond genes are recessive -- which means that if there are genes for another hair colour in my DNA, that other hair colour is likely to dominate -- I turned out brunette with a lot of red in my hair, so that I'm almost auburn. How does evil fit in here? Is evil recessive or dominant?
Lex said often that he had a darkness inside him. Well, as Clark used to point out, so does everyone. We are all capable of evil, whatever we like to think. That's because evil acts are usually based upon selfish wishes, and a desire to dominate other people and have what we want. Evil is based on hatred for others, because they have something we desire, or because they're living and breathing and we feel dead inside. Everyone is born selfish, and wanting and needing things that other people have. A baby is utterly helpless and needs to be fed and cared for, or else he or she will die. And so babies scream and cry and demand out of necessity. We're all like that at birth, but gradually grow up, become less helpless and learn to get along with others without killing them. :-)))
Now, Lex said he had darkness inside him, right? How would someone Born Evil notice this? Someone Born Evil, evil from birth, wouldn't notice or care. For that person, doing evil things would be like breathing, I would assume, because all they care about is themselves, ever, being incapable of growing up and learning to get along with others and wait their turn. They are like children inside, who take what they want without giving. And yet we saw Lex care a lot about others. We saw him quite capable of getting along with others, giving to others, and getting what he wanted, without killing. A truly evil person from birth would be unlikely to care what others thought of him or her, but Lex did.
This is all just a retcon, to simplify the show and diminish any responsibility Clark may have had for Lex's actions to protect the world from dangerous aliens. If Lex was Born Evil, nothing Clark could have done would have 'saved' him. Case closed.