Standing in a half circle round me, eyes as wide as dinner plates, and voices which sounded like gunfire, I felt incredibly uncomfortable, even though I love to talk of the possibility of God, and Afterlife, and evolution.
Well, tell them that. Nobody has a right to put your spiritual beliefs to the question, or bully you into belief.
Tell your family that you're more than happy to answer questions about something you're interested in - biology - to the best of your knowledge, but that your individual spirital life isn't something you expect to have to justify to them. Nobody walks your path but you. Let them know how uncomfortable they made you, and don't let them play it off like "that's God's way of trying to reach you." (There's honestly no feeling or situation evangelical Christians won't try to capitalize on to convert you.)
Let them know that the science of biology and evolution are definately on the table, and you'd like whatever opportunities they have to correct their misunderstandings, but your personal faith is definately
not on the table, and they have no right - indeed, should be deeply ashamed of themselves - for presuming to know better than you in that regard.