I sincerely love my nieces and nephews.
However, because there are SIX of them (three girls, three boys), I'm always anxious before they come over. Frankly, I dread their arrival.
It always gets better once they burst through the door though. The youngest are twin girls, and it's just incredible how aware they are of each other. They're still babies, but they will reach out and hold each other's hand. If I'm standing next to my older brother (their father) holding Twin1 while he's holding Twin2, Twin1 will inevitably reach out and rest her hand on her sister's shoulder, or maybe pat her sister's back. It's so fascinating to see them doing these seemingly learned behaviors like holding hands and patting backs, and realize that it's innate. And admittedly, they are very, very good looking babies (I think being born via C-section and not through the birth canal helped to not squish their heads into weird shapes).
But if they start talking in some whacko twin language, I'm going to be seriously disturbed.