Quark's nephew Nog joined the Starfleet in clear defiance of stereotypical Ferengi values. In fact, his character throughout the series is rather counter to what one may usually expect of a Ferengi.
Conversation from Deep Space Nine: Heart of Stone
Nog: I want to join Starfleet. I want it more than anything I've ever wanted in my life!
Commander Sisko: You're a Ferengi. Why would you want to be in Starfleet? Where's the profit in it?
Nog: I don't care about profit!
Commander Sisko: Then what do you care about? Come on, Nog, tell me! Why is it so damned important that you get into Starfleet? Why're
you doing this?
Nog: Because I don't want to end up like my father!
Commander Sisko: Your... father?
Nog: That's right, my father. He's been chasing profit his whole life. And what has it gotten him? Nothing! And you know why? Because
he doesn't have the lobes. And neither do I.