you learn morals, as well as many other things, from watching how the people around you respond to things. if your parents are racist, you have a much higher probability of becoming one yourself.
if you parents aren't racist, and have multicultural friends, that's whats normal to you.
if your parents aren't religious, and don't go to church, then chances are you aren't, and don't.
people have a negative reaction to some things, so those things eventually become "immoral"....they disturb society in general, and aren't acceptable in polite company.
a long time ago, everyone wandered around pretty much nude. then once people started staying in one place for a while, they had time to make clothes, and time to make them not only serviceable, but attractive. more people started wearing them, and people got used to it. now the nude person is not acceptable in public. no one is surprised at the equipment, we've all seen it before, but it's still somehow shocking...
"morals" aren't inborn, they aren't magic, they're the result of the attitudes of the people we live among, and our own life experiences.