That's like saying you don't believe in monsters, yet refusing to open the closet. Your morals match exactly what you would do. What you say about your morals doesn't. What you are is what you do, after all, not what you imagine yourself to be.
We have instinctual behaviour that leads us to group cooperation, avoiding theft and murder etc. A lot of our morality and legal systems stem from this.
On the other hand instinct can lead people to do some seriously shitty things and we try to suppress it in those cases.
Morality is a code or system of conduct that you aspire to in order to become a better or more virtuous person. We derive some of it from instinct and some from philosphy.