It's the oldest practice in the book. Once you guys have reached the inevitable age where you are all relatively the same size, each other's clothes become fair game.

It's weird, one minute you're wondering how in the world you are related to this thing and then the next you find yourself seeing more of you in her than you ever imagined. But all blessings come with a curse.

Maybe the fact that you share the same DNA is to blame for similar fashion tastes; either way, the only way to battle the cruel irony of your sister magically having cuter clothes than you is a flawless execution.

Follow these easy steps to commit the perfect crime:

1. Timing

Timing is absolutely everything. You need to know the art of the perfect moment, whether it be the second she left the house for a hot date or the night before she is (or you are) heading back to college. You need to know when to strike. It's best to wait until you know she's going to be gone for a good chunk of time before you creep into her room once she's gone.

PRO TIP: For extreme stealers, try rummaging through the bathroom hamper when you're about to do a load of your own laundry. It's dirty so it's far from her mind and she won't suspect a thing for weeks.

2. Hiding

You can't just hide the clothes or jewelry amongst your own stuff, she's just going to find them when she off doing the same exact thing to you a week later. Hide jewelry in small draws and clothes under beds or blankets. Empty suitcases in your closet work the best.

PRO TIP: If you’re attempting to steal your goodies away for your next semester at college, then start transporting your clothes in laundry baskets. When you leave it just looks like piles of folded clothes and she’s less likely to go through it before you leave.

3. Execution

Layers are your best friend when you're leaving the house, or pockets to stash jewelry in until you're in the girl's bathroom before homeroom. Even if it's 70 degrees out, you're going to want a sweater to hide the shirt you stole from her the night before when you two are leaving the house at the same time. The minute you're out of her sight, ditch the hoodie and strut the super cute outfit you've been planning for days.

PRO TIP: Avoid photos and snapchats at all costs. The more social media exposure you have wearing her stuff the more of a chance she’s going to have receipts and bust you to your mom later.

4. Prevention

You just wore her jeans to that big group date to the movie theaters last weekend, but you just caught her wearing your earrings in sixth period, HOW DARE SHE. In order to keep it so it's only okay when you do it, keep your room and car locked at all times and always supervise makeup sessions in your bathroom. You've been there, you know exactly what she's capable of.

PRO TIP: Coming back home for break to a sister with sticky fingers? Leave everything you don’t want her to get her hands on (or that you took from her) safely in your dorm room and out of her reach.

Good luck out there sisters, and may you always win future installments of "Who Wore It Best."