Answer the questions based on the information given below. In a family of three generations, there are seven members R, S, T, U, V, W and X. R is the mother of X. X is an unmarried member. T is the brother-in-law of X. V is the grandmother of W. S is married to V. U is the son-in-law of S.
If U has only one daughter, then how many male members are there in the family?