Answer the questions based on the information given below. There are eight persons O, P, Q, R, S, T, U and W in a family of three generations. R is the father of U, who is the sister of W. W is the brother-in-law of S. Q is the child of S. Q is married to P. T is the husband of O. T has only one child, who belongs to the 3 rd generation. How is R related to S?