7 surprising facts about siblings

Siblings can be annoying, but you usually love them anyway. After all, they share half of your DNA.

Scientists have studied how having brothers and sisters in different combinations can change people's lives.

Research has shown siblings can affect your intelligence, your mental health, and even your height.

Sibling studies are tough to do, though. It's difficult to make sweeping generalizations about so many people, so these findings won't apply to everyone.

But here are 7 surprising facts scientists have discovered about siblings.

Studies have found younger siblings can be funnier and live longer.

Sources: University of Chicago's Center for Aging, BBC News

People tend to form relationships with partners who are of the same birth order as they are. So if you're a middle child, you could be more likely to marry a middle child.

Source: Journal of Individual Psychology

In one small study, men with older sisters were more likely to talk to and flirt with women.

Source: Journal of Personality and Social Psychology

Another study found that having an older sibling was linked to better mental health than having a younger sibling.

Source: Social Science & Medicine

If an older sibling is on the autism spectrum, a younger sibling can be at a higher risk for developing autism, too. Researchers have had trouble calculating the exact risk, however.

Sources: Pediatrics, EARLI study, Journal of Autism and Developmental Disorders

Older siblings tend to have slightly higher IQs than their younger brothers and sisters.

Sources: Science, LiveScience

A large study of British families found that in families with four kids, younger siblings tended to be about an inch shorter than average. The youngest child had the biggest height difference.

Sources: The Guardian, International Journal of Epidemiology