Males : 4
As per the data:
S is P’s father and U’s grandfather. -> S is a male
R and U are brother and sister and children of P. -> either R or U is a male
Q is the brother of T’s husband. -> Q is a male and T is a female
As T is a wife, we can imply that P and T are married.
This explains that P is also a male.
Therefore, S, P, Q and U/R are males in the family.