I have 2 identical twin kittens who won't leave human food alone. Suggestions? We don't starve them I promise.?

I have 2 identical twin female kittens, whom have a fascination with human food. We got them through a friend of a friend.I'm trying to teach them that cat food is for cats and human food is for humans.When they even hear us in the kitchen or on our way there, they'll get so bad as to trip you to get the point across that that's what they want. Or, they will bombard my fiance's mother who's elderly, and they won't let her eat in the living room in peace as they will jump up on you to get to what they want.They don't really care if they claw you to get to it. We don't starve them as they always have an ample supply of food left out as well as continuous fresh water supply. We try telling them no, chasing them off(they just come right back a few moments later), we've tried everything. Any suggestions out there??? I really don't believe in hitting animals, so whats an alternative i can use?