Why are most kids so annoying?

I was at a cousins birthday party and the five cousins that aren't related to me are extremely annoying. The eldest, an 11 year old who looks like a freaking 17 year old (she's taller than me and i'm 13 O. O) is way too loud and rude. She brags that she dated like 11 guys and has an iPhone 5, she mocked me that i never had a girlfriend before but even I'm not allowed to date until college. Her 10 year old brother cusses way too much. Her 8 year old brother constantly argues with her 7 year old sister on who gets to play with the ipad. And the four year old sister screams so loud every time she cries that it hurts my ears. I'll admit, I'm still a kid and occasionally, I'm annoying too if I ate too much sugar or if I'm stressed out which is one of the many reasons why I'm asking this question. Were kids generally like this before? Or is it just today? Well I wouldn't know, I wasn't born thirty years ago.

Children are pretty much the mirror of their parents.

Hopefully they grow out of it and don't become annoying adults

Those kids you describe may have been spoiled & not taught good manners. Or they may have got away with misbehaving & come to think it's the right way to behave. Bad behaviour certainly gets you noticed, & gets what a lot of kids crave, which is attention.

There have always been kids like that. But I think the general feeling is that generally speaking standards of behaviour & standards of parental responsibility have declined a lot. I wouldn't know, it may be that nowadays we're just more aware of what goes on than we used to be 30 years or longer ago.