LOL I have been there! My first chin was a "he", the breeder said so, the vet said so, and I thought so. I bought a male cage mate for my boy...111 days later one of my "males" had a baby! It was very interesting trying to figure out who the mommy was. Turns out I just had a very "male-looking" female. Which was fine, because that is how I ended up getting into breeding, which I love.
It happens sometimes. Especially when they are young it can get pretty tricky trying to tell the difference. With some males it is very obvious, there will be a large space between the penis and anus, but sometimes the space can be very small, making him look like a female. The space doesn't become more obvious until he gets older.
