Answer:
the only amusing part of the body
Adored by few, feared and hated by many. Mistress of the entire universal reason, master in the art of numbers. Some may have solved many of my mysteries, but there are still many of them to find. What am I?
What can be as big as an elephant but weighs nothing?
I run around the city but I never move.
I love to twist and dance. Though wingless I fly high up into the sky.
I am your mother's brother's only brother in law. Who am I?