© AntonioGuillem/Getty Images Here's why you don't want to be your mom's favorite child

It's a story every sibling knows by heart: Mom has a favorite. She might say otherwise, but you all know it's true. It's usually you, because you're awesome, but if it isn't, you know it, and you probably know it from a very young age. In a best-case scenario, Mom's favorite varies from year to year or even from day to day, depending on who is acting a fool on any particular occasion. In a worst-case scenario, Mom has a true golden child who can do no wrong, and no one else can ever measure up. For those kids, the effects are devastating and long-lasting.

A new study published in Oxford's Journal of Gerontology: Social Studies puts a twist on that old narrative. It turns out that in a family where Mom plays favorites, the kids who get shafted aren't the only ones at risk for things like depression and drug use. The favorite child feels the strain too.

The study took data from 725 adult children in 309 families and determined that when a child perceived themselves to be more emotionally close to their mother than their siblings are, they were at a higher risk for long-term depression, possibly owing to the fact that the child will sense the discordance between themselves and their siblings that results from that favoritism. Additionally, those children feel a stronger sense of responsibility for the "emotional care" of the mothers who doted on them in youth, which is a pretty big burden to bear.

It really doesn't take a lot of heavy-duty science to determine that if you play favorites with your kids, there's bound to be some fallout. Most parents claim not to, but there's one thing that's particularly important about both this study and a separate study that came out earlier this year about parental preferential treatment, published in the Journal of Family Psychology, and that's perception    

In both studies, the way kids perceived themselves and their parents when it comes to who the favorite sibling is played a big, big part in the results. In fact, the second study showed that kids who thought their parents were favoring a sibling were more likely to act out — even when they were actually being treated fairly.

That means that if you're the type of parent that pits child against child in a battle for your affection, even if you know in your heart that there is no way you could love one more than the other, it's time to knock it off. Ditto to the "that's why you're my favorite" jokes and the flippant conversations you have with your friends about which one of your kids is your current favorite when your kids are in earshot.    

There's more to it than that, though. Most of us don't go around announcing which child we love best today, but kids pick up on nonverbal cues just as much as any of us do. Chances are, whether or not you actually have a golden child is beyond the point. Parents of siblings will have to deal with accusations of favoritism all the time. It's up to us to prove our kids wrong.

Luckily there are time-tested techniques that experts suggest you can use to keep run-of-the-mill sibling rivalry from turning into full-blown perceptions of favoritism:

First, it's important to treat kids fairly. If one of your children requires your extra attention, your other children may not see that for the challenge it is. Even if the attention is doling out discipline or soothing a tantrum, your other kids will see that as time they're not getting. So make sure you give your kids equal time and a chance to be with "just you."

Next, look for signs from your kids that will clue you in to your child's suffering self-esteem. A child who feels like they aren't getting enough attention will usually either withdraw or act out. If it's out of character, something's up.

Finally, talk to your kids. Help them understand why you do what you do. Why one sibling might get a little extra attention while you trust another to handle things on their own. Make sure they understand that they enjoy the same unconditional love their siblings do and that nothing they can do will change that.

Don't just assume your kids know you love them all the same — make sure they do by reminding them every single day or until their eyes roll right out of their sockets when they get tired of hearing it.