There's a reason why the exclamation "Oh, brother!" exists rather than "Oh, sister!" It's because brothers are a force of nature, creating a vortex that's felt far and wide in a family. Anyone with a brother knows this, as well as moms whose broods include the male species. And now we've got indisputable scientific evidence this is true. Check out the surprising ways brothers impact their family members below — like by attracting suitors for their sisters but then preventing them from having sex, turning their younger brothers gay, and more.
Whoa, do you believe #6?
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Brothers Raise Your Blood Pressure
Brothers, specifically younger brothers, will raise other siblings' blood pressure, according to a Bolivian study. The possible reason: Younger brothers suck up their parents' attention and place a greater burden on older siblings to keep it together.
Brothers Snag Their Sisters More Dates
All that brotherly love cultivates sisters who are awfully chummy with the opposite sex: One study found that women who grew up with older brothers were more likely to talk to and smile at a male stranger. This bodes well once they start to date.
Brothers Keep Sisters Virgins Longer
Little brothers really can be pests — to the point that their older sisters don't have sex. An Australian study also found that presence of younger brothers delays how soon their sisters engage in sexual activities by more than a year.
Brothers Keep Sisters from Getting Their Period
Brothers, it turns, out, don't merely scare off their sisters' suitors, but can put the brakes on their budding sexuality in other surprising ways. That same Australian study also found that the presence of an older brother delays a sister's onset of menstruation by a year on average.
Brothers Make Men Fertile
Strange but true: A study by the University of Sheffield found that the more brothers a man has, the faster his sperm swim and the greater his fertility. As a result, researchers also theorize that families with high fertility are more likely to have boys.
Older Brothers Could Make Younger Ones Gay
A study by Brock University in Canada found that older brothers boost the odds that younger ones will be gay. According to data collected on over 700 homosexual men, a firstborn brother has a 3 percent chance of being homosexual, while a fourth-born brother's odds double to 6 percent. Researchers chalk this up to the "maternal immunization hypothesis," in which the mom's production of antibodies that can impact sexual orientation increases with each successive birth.
Brothers Are a Bad Influence
Bottom line is brothers truly are trouble: Research from Wichita State University found that deviant behavior by older brothers increased the risk of younger siblings dabbling in risky behavior, from drugs to sex. This did not hold true for sisters. (Why are we not surprised?)
More from The Stir: 13 Surprising Scientific Facts About Siblings
