So for the past 2 weeks DS has been insisting that I do not have a "boy" or "baby brother" in my belly, but have a "baby sister" in there. He is starting to get frustrated when we ask if its a boy or girl, or ask "what if its a little boy, or little brother". NO mama, my baby sister! I wonder if he's right?? He's almost 2...wondering if he really knows the difference? Have your LO's guessed the sex of their siblings?