What does this rebus riddle means ?

What number should come in place of the question mark below?

There were two grandmothers and their two granddaughters.
There were two husbands and their two wives.
There were two fathers and their two daughters.
There were two mothers and their two sons.
There were two maidens and their two mothers.
There were two sisters and their two brothers.
Yet there are only six, who are buried here,
All are born legitimate and relationships clear.
How can this happen?

Jack have ten pairs of black socks, eight pairs of white socks and seven pairs of green socks. Everything is mixed in a draw. As there is no light he were not able to identify the colour of the socks. How many of the socks did he want to take to match one pair

I look at you, you look at me I raise my right, you raise your left. What am I?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

Only one color, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

P is the father of Q and S is the son of R. T is the brother of P and has a daughter U. If R is the sister of P, then what is the relation between U, Q and S?