Yes Human nature can be changed. It has been changing ,is changing & will be changing.
Human nature as a distinct byproduct of Evolution -
Take the feelings of ,
being afraid of arachnids(due to them being poisonus & easily hiding in the caves & dirt ) ,
to wanting to be near fire (fire kept primitive humans warm at night & discouraged predators) ,
to liking pets (primitive humans domesticating wolves in a bid for shared survival ..& later companionship)
..all these feelings are byproducts of mans past changing his nature to be able to better survive.
Human nature is already changing due to modern life & scientists are saying centuries later it will add upto & make a very different human with different social norms & nature .
So you can say Human nature is a product of its surrounding & if surroundings change then Human nature can be changed.& it is already changing.
Human nature as a distinct byproduct of Culture -
Culture to a very large extent affects Human nature -
Take our food habits
... in the west people like chicken,beef,pork etc - because these are plentiful ,tasty & what they have grown up with...
BUT contrast this with China where some people eats insect,snake & has a dog eating festival.
Now this is gross to west ( but why? ...insects are per pound more protein than anything,gives great energy...because thats how the west grew up ..Insects are gross & dangerous. No eating them .even if you cook them properly .)
or dogs (Objectively speaking they are mammals with 4 legs & meat on their bones like A cow or a pork. So why differentiate between eating any of them ..Again culture !
Chinese certainly keep dogs as pets but some place dont .Those places always have seen dogs as food & it has become an element of their culture & so even in modern times that few places likes eating dogs )
Now take a Chinese baby from some of those dog eating places ,give him a pet dog
..let them stay together ,play together,become best friends ... for several years in another place with no mention of dog being a food ever being hinted at him ..
Then Tell him that he has to eat his best friend(the dog) ..see how he reacts ..he'll probably try to kill you or faint in horror.
That is the power of culture..Nurture over nature..It changes Human nature.
Should it be changed ? ...well,See all these is a matter of gene ,you edit the gene ,you change Human nature
This is a matter of much debate ,with much division ... selective evolution with the best traits of Humans being given pritority or keeping neutral ...its a matter of ones opinion ..