I believe that things, including people, exist in time, and it is perfectly reasonable to refer to something as what it was or will be. A object is never really a boat if it never touches the water, but you might still call it a boat while it's being made and after it's beached for good. Most children you can reasonable identify their future reproductive capacity from day 1, in much the same way you can say a log is a canoe if you know you're going to make it into one, but whether they are that thing at that point is a philosophical question without a clear answer. Is something defined by a certain purpose meet the definition before it is actually capable or after it is not? I don't know. But, what is clear enough to me, something that cannot fulfill a purpose will never meet the definition, making the time aspect certainly moot.