Complex sentence: María Laura hires Andrés by chance, and remembers their 1989 encounter; a DNA test confirms that Andrés (not Pablo) is the father of her son, Martín.
Split into simpler sentences: María Laura hires Andrés by chance, and remembers the 1989 event. A DNA test confirms that Andrés, not Pablo, is the biological father of María Laura's son, Martín.