If your mother spat out a few boys already before you came along, then you know the pain of having your older brothers constantly questioning your sexuality. You may be interested to learn that, according to science, they were right to do so: Having older brothers increases the probability that you will be gay.

It's called the Fraternal Birth-Order Effect, and it's quite clearly documented. For each son a woman produces, the chances that the next one will be spending his first 20 years inside a closet increase by 28 to 48 percent. By the fourth or fifth, you might begin to notice a puzzling affinity for musical theater.

Now, keep in mind the base rate of homosexuality is low already, you would need over 10 brothers before your probability of being gay propelled over 50 percent. Still, it's estimated that one in seven gay men can attribute their sexuality to this effect.

And they can take one hell of a photo.

Scientists think that this phenomenon is caused by a mother's body reacting to her son's foreign dude-proteins, and making antibodies to fight them. Each time another boy passes through a woman's system, these antibodies get stronger, and their target is your masculinity. We wish we were making that up. Before you're even born, your older brothers actually gang up on you and attempt to beat the straight out of you for nine months.

Why? They think one factor is that, along with stinky second-hand clothes and a beat up backpack, the youngest has to make do with a stretched-out, hand-me-down uterus. As a mother goes through multiple pregnancies, she tends to put on weight, has worse blood sugar and generally stops giving a f**k.

"Screw it. The other two are smart enough."

It's like making three pizzas. The first one gets all the best ingredients, arranged carefully in a perfect ratio across every slice. For the second one, you find that you've run out of cheese halfway through, and you kind of just throw everything on there. For the third, you s**t on the pizza just to see how it turns out. If you're the youngest in your family, you are that third pizza.

Then, after you're born, it turns out that not only do your parents love your older siblings more than you, they also spend more of their household's available resources on them. There is simply less time, money and attention available to a family's youngest child.

In big families, parents cannot provide proper nutrition to their youngest children, presumably because after years of responsible child rearing, they decide that owning a feral scavenger might be a fun change of pace.

"Honey, I think I know how we can save some money on our grocery bills..."

It's for similar reasons that...

Anyone with an older brother or sister has shared this pain. No matter how hard you try, your older sibling always seems to come out ahead. Upon realizing that your parents actually went to that sibling's athletic events, hugged them and even gave them real meals rather than your two daily bowls of expired dog food, you decided that, if you hit the books hard enough, you could at least surpass your elders academically. Curing cancer will show them all!

Great science is driven by deep fear of inadequacy.

Nope, sorry. In a recent study analyzing over 240,000 subjects, researchers found that, on average, the eldest sibling scored three points higher on an IQ test than their younger kin. Three points may not seem like much, but it can be the difference between receiving a nice fat acceptance envelope from Yale, and having them send you a rejection letter nailed to a dead possum.

We've already explained how your older kin get the lion's share of your family's resources, but it turns out that they also get the best education during the crucial infant years. Before you and the other homewreckers came along, your eldest sibling secured your parents' undivided attention for however long they were Mom's #1. Logically, each subsequent child divides this attention, and you only wind up with half, or a third, or a quarter of the time and dedication that the golden child ever had.

Scientists think that this head-start leads to higher vocabulary and reasoning abilities, and because the younger children are increasingly faceless members of a growing litter, they never have a chance to develop the same brainpower. It's called the dilution hypothesis.

But there's more. As the family grows, older siblings begin to take on some of the responsibilities of their fed-up parents. This means often that they become makeshift tutors for their dumb-as-a-brick brothers and sisters. Ironically, because teaching something is the best way to learn it, this benefits them more than it does you.

By this logic, teachers are the most selfish people on the planet.

It may seem altruistic that they would act as your mentor, but what they're really doing is reinforcing the fact that you will never be better than them. Ever.

OK, it's not all bad news for the younger kids. Our big brothers and sisters may be smarter and taller than us, but studies show they're not as healthy.

It has been found that the risks of hay fever and eczema decrease when you've had three or more older siblings. Having multiple filthy children share a household tends to convert the place into a giant Petri dish, but because infections lend strength to a developing immune system, the various exotic diseases that kids bring into the home wind up benefiting everyone involved.

The picture of health.

The kick in the pants is that, even after granting you an ironclad immune system, your sickly older siblings will still outlive you.

Scientists at the University of Chicago have concluded that if you want to live to a hundred, you damn well better be a firstborn. Apparently, the secret of the firstborn's success lies in the mother's birthing age. If the mother is below 25 when she propels her first spawn out into the world, that child is much more likely to eventually become a centenarian.

The study showed that, for women, the firstborn child is three times more likely to make it to 100 than the seventh sister and beyond. Firstborn males are twice as likely to reach 100 as male siblings born fourth through sixth.

They'll be enjoying the sweet fruits of incontinence and senility while you're rotting in the ground.

A possible explanation to this phenomenon is that younger mothers tend to have healthier eggs, and are generally healthier than their older counterparts, having had exposure to fewer diseases and infections over the course of their lifetimes. After the eldest kids arrive and start acting as dragnets for every biological hazard within the same time zone, the mother is exposed to more disease, and since her best eggs have already been spent, her future children wind up being short-lived little mutant goblins.

On the plus side, you get a better shot at a circus career.

Holy crap, is there any advantage to being the younger brother in a family?

A study in which subjects were placed into a speed-dating-like environment has shown that having older siblings of the opposite sex is incredibly socially beneficial. Men with older sisters were significantly more conversationally adept, and women with older brothers were likely to strike up a conversation with a man, and smiled more at the man than he did at her.

Apparently, your older siblings increase your empathy skills to counter their sociopathic bent. In addition, any type of sibling in general makes your social skills throughout life skyrocket. You'll get along better with other children in kindergarten, have closer friendships and generally have more fun than your overworked elders who struggle under the burden of perfection.

Younger siblings are funnier too. A study showed that over half of younger siblings said that it's easy to be humorous, compared with only one third of oldest siblings. Only-children were worst off, with only 11 percent claiming to be funny. We take this one with a grain of salt, because often the people who claim to be funny are really the most groan-inducing douchebags in the room.

Both of these men are "hilarious."

It's theorized, though, that younger siblings have to compete more for attention, so their people-skills muscles get so much more of a workout. And why not? When you struggle through life as a possibly closeted, academically average midget who doesn't have long to live, it really helps to have a sense of humor.

Or religion.

For more ways our families screwed us up, check out 7 Things 'Good Parents' Do (That Screw Up Kids For Life) and 9 Toys That Prepare Children for a Life of Menial Labor.

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