I certainly have never had a problem with being veggie/vegan when it comes to lacking nutrients. And I've never been a routine taker of vitamins and supplements as I believe you everything you need is in food if you properly balance your diet.
I remember me being a vegan mum-to-be back in the 90s causing an enormous fuss with the midwives. I hope things have improved since then!
I don't know about genetically programmed. I think anyone can successfully switch to a veggie or vegan diet if they research properly. How difficult they find it is often more to do with the reactions of their friends and family than anything else.