It's likely way too early to tell and is probably a recessive trait as the other kids have the straight hair (law of genetic averages).
Our son's hair curls only when it's really humid out but is stick straight through the more arid winter months.
Our daughter was like yours and had curls when her hair was wet but straightened as it dried. She's now 2 and has stick straight hair that is gorgeous.
I have always had VERY straight hair and always wanted curls. I love curly hair. But, my kids both have gorgeous hair - different, but completely gorgeous.