If its realy important for you to know the sex of your baby you can have it probed at a vet.If you do have it probed make sure the person knows what they are doing as you could hurt it.Ball pythons can be sexed from the time they are about two weeks old.Where did you read you can tell the sex by the way they act? I breed ball pythons and have never heard that.I am not doubting you just never heard it .