On that note, is being content a skill most can learn with effort or does it have significant biological prerequisites (genetics, prenatal environment, etc)?
No idea, but one thing is that it's probably better to operate under the assumption that you can overcome such irrational tendencies, and have a goal or outlook to grow in that dimension, rather than resigning yourself to "welp, I'm going to act stupid now and there's nothing I can do to improve this".
You can experiment with this very easily for yourself by asking yourself what problems you have right this moment. It turns out you never have problems when you have the time to ask yourself that question. The book The Power of Now is well worth reading. Most importantly, Tolle doesn't ask you to "believe" or have faith in what he says, just that you try it. And it works :)
Tell that to everyone who comes to terms with it and is at peace or is content and thankful for their situation?