I just answered this same question. Is there something wrong with the answer I posted?
The sample space is:
B B B **
B B G *
B G B *
B G G
G B B *
G B G
G G B
G G G
There are eight possibilities. Three of the possibilities have two boys (*), and one has three boys (**).
So the probability of EXACTLY two boys is 3/8. The probability of AT LEAST two boys is 1/2. What the question means by "two boys" is a matter of interpretation. You choose which is the correct way to look at it. The sentence as written is ambiguous and could mean either exactly or at least.
John

My calculator said it, I believe it, that settles it