Shem then?

Sure doesn't seem like we are of Cain.

I've believed for a few years now that those that have a built-in criminality and predisposition to harming children are from Cain.

Well, let's go back to the beginning. Besides Cain, there was Seth. Then, the flood came and whisked everyone away except for Noah, his wife, his sons, and his daughters-in-law. Noah surely would have been of the line of Seth. Most likely, his family members would also have been descendants of Seth. Even his daughters-in-law, though we don't know for sure.

Shem was one of Noah's three sons. It is thought that Ham was black, Shem was Semitic, and Japheth was light-skinned. The word Semitic comes from the name Shem.

The most important thing to remember is not so much the DNA of a person but the SPIRIT of a person. Even if every single descendant of Cain was taken away in the flood, the spirit of Cain (being all about one's self) can arise in anyone.

Example: Gideon was a very righteous man whom God chose to war against the Midianites with 300 men. After Gideon died, his son, Abimelech, was EVIL. Even within a nuclear family, there can be good and evil. Each person chooses.

This is question, I asked myself so many times. Abel was the first, who made a blood sacriface, while Cain gave the fruit of the fields. Did God really choose the blood sacriface and rejected Cain ? Maybe the Cabal told us the wrong story was had happened ?

I believe what it says in the Tanakh (what Christians call the old testament).

If you read that story carefully, you'll see that Cain had no regard for God; not in obedience, didn't repent when give the chance, and got snarky with God. Cain was all about CAIN. "He's making me look bad!" is the sort of thinking that made Cain kill his brother when, in fact, Cain made himself look bad.

It's the same reason Saul sought to kill David and the Pharisees sought to kill Yahshua.