My kids are fairly well mannered for their age and station in life. They can eat at the table without over-turning it, mostly. They have been known to say "please" and "than you". They generally behave in stores and other public spaces. Really, I have seen worse. Where my kids (and I do not think I am alone here) seem to display their most raw mammalian selves is in the area of body investigating/fluid exchange/jam handedness.
In the hour after bath, before bed Tennessee held his penis between his thumb and index finger in order to poke it up against his dad while saying "peck, peck, pecker" then cracking up. While I painted Lucy's toenails bubble gum pink he sat next to her picking his nose with one hand while holding the other out to me repeating "polish on my nails too!" over and over. Later I caught him wiping his nose on the sofa like a total freakin' barbarian. I squawked tissue box squawks, pointed and hooted. He ran a tissue over where his mustache will someday be, then tossed it over his should onto the rug. I groaned and huffed. I know this isn't forever. I know my squawking and his future desire to date will mold him into a tissue using citizen of the world. I just know it will all come together one day. I believe!