If you didn’t horribly flunk out of high school physics as I did (I was always better with Shakespeare than the science of space and time), you probably studied Einstein’s Theory of Relativity. I still have no idea what it actually means, but since I love words, I came up with my own theory of relativity. Or rather, theory of travel relativity.

It goes something like this: the measure of travel costs should be considered in relation to the destination. However, your fundamental interactions with far-flung relatives can make the empirical discovery of new, exciting locations possible.

Okay, I actually have no idea what most of that means and just tried to make it sound impressive (which I was convinced through most of high school is what Shakespeare did too).

Here’s the layman’s definition: It costs little-to-nothing to stay with your relatives when travelling. Vacationing with a family costs a metric ton of money. If you come from the kind of background where relatives feel an obligation to you because of your kinship, even if they don’t actually like you, and you can at least tolerate them in return, it can mean free accommodations in a place you want to visit and explore.

Make no mistake though; there’s a science to this too. If you want to stay on everyone’s Christmas card list, here’s what not to do when lodging with loved ones.

Don’t:

• Call mere days before (or the day of) you’re travelling to their city to let them know you’re coming and expect they’ll accommodate you on short notice. No matter how close you are to them unless it’s an emergency, most people don’t appreciate the eleventh-hour call and lack of proper time to wash the sheets and hide the bodies.

• Leave your departure date ambiguous or change it. No matter how much your family loves you, there’s a 98 per cent chance they’ll be using an app on their mobile device to count down the days until you leave and they have their normalcy back. Leaving it open-ended or extending it will crush their spirits, make them invoke an old family curse (nobody needs that) or at the very least, potentially annoy or inconvenience them and any plans they’ve made.

• Assume they won’t expect to see you during your stay. You didn’t want to pay the $169 fee for a hotel room, so don’t treat a relative’s home like one. They may want terribly cumbersome things from you, such as conversations with actual dialogue and complete sentences, instead of a quick, shouted greeting as your breeze out the door for a day at the beach. Indulge them. Your kids just rubbed jam from breakfast all over their door handles. It’s the least you can do.

• Speaking of which, here are the appropriate topics to discuss over the dinner table: weather, local attractions, your favourite member of One Direction, and if you’re kind of close to these family members, a healthy debate on why The Bachelor is real TV. Don’t bring up their long-held feud with your aunt, even if you’re dying to know their side. It should go without saying but also do not discuss wills, family fights or why you no longer attend church. It’s a vacation. If you really wanted to have those conversations, you could have just called your mom and saved yourself hundreds or thousands of dollars.

• Drink all of their booze. Emptying their liquor cabinet is a surefire way to ensure they’re coincidentally out of town or fighting a nasty case of tuberculosis whenever you inquire about staying in the future. Show up with some in hand for them as a thank you, plus bring your own to drink. If you did just want a free room and anticipate it will feel much longer than your planned four-day stay, bring more than you think you’ll need.

If you manage to mess this all up, remember: blood may be thicker than water, but water is a primary component of vodka. I’m pretty sure that flows through and unites us, even scientists and The Bard.