Your question is funnily worded btw.
Four families have four children each, find the probability that at least one of the families have two boys and two boys?
The answer is around 0.8.....
-------------------------
P(Any one family has 2 boys 2 girls)
= 4C2 * (1/2)^2 * (1/2)^2
= 0.375
So,
P(At least 1 family has two boys and two girls)
= 1 - P(No family has two boys two girls)
= 1 - (1-0.375)^4
= 0.847...