There are two possible answers to this question, depending on whether you consider the wives of the sons to be part of the family or not.
Suppose the wives are not part of the family.
Then we have:
Total children of sons
= 6 * 4
= 24
Total people in family
= parents + sons + children of sons
= 2 + 6 + 24
= 32
Suppose the wives are part of the family.
Then we have:
Total children of sons
= 6 * 4
= 24
Total wives
= 6
Total people in family
= parents + sons + wives + children of sons
= 2 + 6 + 6 + 24
= 38