I have 2 kids, a year and a half apart.
It's great- because they entertain each other, and even though I have to play referee many times a day, they're the best of friends.
Although they screw me up on the family deals when it comes to extra activities, because they don't like to do the same thing; one's in ballet/tap, the other is in karate- both of them girls. It makes me mad because I don't get the discounts...
Oh and I'm an only child. I don't agree that it screws you up. I'm fine.
...I think.