Well, it's not exactly a question is it?
I suggest that you were a bit blunt. When the kids (now late teens) ask if I believe in santa claus I still say yes.
I think you can, in the same spirit (pardon the pun), say you do believe in Adam and Eve (to the degree that you believe in god or are agnostic about it).
What makes us human (please refer to catholic church's position on this too) is NOT the bodies that we inhabit; it is the our natures (our spirit for those so inclined -- but not me).
One can choose to believe that god "breathed" this spirit into the animal shell and in fact did it to just a pair of early humans about 200,000 years ago.
Of course, others here would say that God is MUCH more powerful than that and set the course of events going 4 or 14 billion years ago knowing that after that time a few millenia ago spirited humans would arise.
Not necessarily just two but only a few in the garden of Africa.
It's too bad that your family choose to believe in such a little weak god but what can you do.