On DNA/genetics:
Life's Greatest Secret, Matthew Cobb
Siddhartha Mukherjee's books: 'The Emperor of All Maladies' + The Gene are very good as an introduction (start off by watching the PBS documentary)
Jim Baggott's books are good on physics e.g. 'Mass'.
Also Jim Holt, though he was trained as a philosopher.
Penrose 'The Emperor's New Mind' etc are very good but not new.