Katherine has said that we are lucky that the boys lack thumbs. My response is usually that since they each have four paws and fangs, it's mental more than physical -- their gifts lie in places other than tool use.
It sucks to be (mostly) right. Even lacking thumbs, they sometimes can play against type and figure out mechanical devices.
Because of this cleverness, we're in trouble. The boys have figured to how to open the standard model of the built in cabinets in the Kitten Farm West, and by standard I mean every kitchen and bathroom cabinet, from under the sinks to over the refrigerator. Which opens up the exploring of places with fragile glass, nasty chemicals, and kitty treats.
Rubber bands have been placed across the knobs of the most critical cabinets. Magnet latches have also been purchased. If the latches don't provide enough resistance, we'll go to child-proof latches.