I agree with flatfootjoe, I assume her clothing was burnt off and breasts would have been visible and I also would imagine that her small size made them assume she was young. IIRC Jessica's aunt shared on twitter that Jessica was barely 5 feet tall and only weighed around 95 pounds.
So we know she was found with her breast showing?
You cannot identity a person's age/sex on size/weight..I know many older people who are that size...men and women..
<modsnip>
Classito