That's the bad(and good) part with my lot. So damn intelligent and persistent, they figure out a way.
I've been tempted to move to child locks, but I'm half scared that by the time they've fully grown, they'll have figured out how to manipulate those. I know at least one has figured out how to unzip my backpack, flush the toilet, and turn on faucets. She's almost gotten down how to turn doorknobs by dangling.
At a certain point the most dignified thing to do is admit defeat and acquiesce. They have a level of time and resources unfathomable to most adult humans.