Your little sister, the baby of the family, has always gotten away with everything.

If you brought home a D on your report card, you were punished, but if she did the same, she only got a stern, "Please do better next time."

Then there's your older sister with her athletic trophies. Your parents certainly loved (and still love) bragging about her. 

And don't forget your brother, the scholastically gifted middle child. Did your parents have to frame every single one of his awards?

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There's so much competition for parents' attention, it stands to reason that all mothers and fathers must have a favorite child, even if they don't want to admit it — right?

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Unfortunately, you'll probably never know for sure which child is your own parents' favorite, as they will continually insist that they love all of their children the exact same amount and in the exact same way.

But as much as parents want people (especially their own children) to think that they don't have a favorite, science says something entirely different.

In other words, research has found that yes, the vast majority of parents totally have favorites. Which means yours probably do, too. And their favorite is often based on birth order.

A recently resurfaced study by sociologist Katherine Conger found that 74% of mothers and 70% of fathers reported preferential treatment toward one child.

Conger and her research team surveyed 384 sibling pairs (each within four years of their sibling) and asked them how they felt their parents treated them if they sensed some sort of differential treatment, and if they felt a positive or negative reaction from the perceived difference.

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The research team then interviewed the siblings' parents for their perspectives as well.

Although the parents didn't say which child they preferred, Conger and her team theorized based on which sibling felt the discrepancy the most.

"Our working hypothesis was that the older, earlier-born child would be more affected by perceptions of differential treatment due to their status as an older child — more power due to age and size, more time with parents — in the family," Conger told Quartz.

However, it turned out that their hypothesis was completely wrong.

Firstborns reported feeling they were the preferred child because, for a glorious time, they were (technically) only children.

Once their siblings started to come along, their status as oldest children made them the first in the family to kill at sports, lead the way academically, and generally challenge their parent's parenting skills.

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Eldest children pave the way, and when those younger kids get to the age of their older siblings, their parents have a better idea of how to handle certain situations and tend to get a little tougher.

Because of this, younger siblings often believe that they can sense the firstborn bias — and it affects their self-esteem.

The research also found that in some ways, birth order didn't matter, as each child was suspicious of their parents liking their siblings more.

"Everyone feels their brother or sister is getting a better deal," Conger said.

To sum it all up, since you'll probably never know for sure which child in your family is your parents' favorite, you might as well go on believing it's you.

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Christine Schoenwald is a writer and performer. She's had articles in The Los Angeles Times, Salon, Bustle, Medium, and Woman's Day.