Under "C" in the dictionary for Creation. In Genesis in the Bible its called Creation.
So you're claiming that every generation has been Created from scratch? Fascinating. Has no one told you about the birds and the bees yet?
Hint: While you've got your dictionary out, look up the meaning of "each generation", and also ponder the logical implications of your claim that there "aren't any" ancestors.
Keep trying, I'm sure you'll get it eventually.
One can't assume that things have always worked as now. In the Bible babies seem to come from people "knowing" each other, just as back in the 1930s babies came from "makin' whoopee."
The first generation of man was created by God. Successive generations did not mutate and become man of today.