just before you read this , this is an theory not a fact
advanced chakra natures are made by combining two elements together however they also require a kekkei genkei. so certain clans such as uchiha, sarutobi, senju, their kekkei genkei influences their chakra nature, e.g. uchiha fire. however only certain members of each clan can make an advanced element, i think that the kekkei gekei gives them a certain chakra nature and depending on the shinobi it could either be their main affinity or if their own chakra nature is stronger than their kekkei genkei chakra nature than that one becomes their affinity, e.g. hashirama is a senju with water style as a kekkei genkei but his affinity to earth is stronger than his water kekkei genkei, i think that the only way to make an advanced chakra natureis to have an two strong chakra natures, that is why you need a kekkei genkei because a shinobi without kekkei genkei can only have a one strong nature but with a kekkei genkei you have one strong one from your kekkei genkei and one from your own and the only way to create a strong chakra nature is o have your own nature stronger then your kekkei genkei e.g hashirama, but other clan members. their own chakra nature is not stronger than their keekei genkei e.g tobirama had an affinity to water then it was wind. kekkei genkei was stronger that his own one.
naruto is an uzumaki and they are a descendent of the senju, so it could be possible that naruto has water style kekkei genkei, and we already know that narutos affinity is wind that means his affinity is stronger that his kekkei genkei and wind plus water is ice, both his natures are strong so it could be possible that he is an ice style user
advanced chakra natures are made by combining two elements together however they also require a kekkei genkei. so certain clans such as uchiha, sarutobi, senju, their kekkei genkei influences their chakra nature, e.g. uchiha fire. however only certain members of each clan can make an advanced element, i think that the kekkei gekei gives them a certain chakra nature and depending on the shinobi it could either be their main affinity or if their own chakra nature is stronger than their kekkei genkei chakra nature than that one becomes their affinity, e.g. hashirama is a senju with water style as a kekkei genkei but his affinity to earth is stronger than his water kekkei genkei, i think that the only way to make an advanced chakra natureis to have an two strong chakra natures, that is why you need a kekkei genkei because a shinobi without kekkei genkei can only have a one strong nature but with a kekkei genkei you have one strong one from your kekkei genkei and one from your own and the only way to create a strong chakra nature is o have your own nature stronger then your kekkei genkei e.g hashirama, but other clan members. their own chakra nature is not stronger than their keekei genkei e.g tobirama had an affinity to water then it was wind. kekkei genkei was stronger that his own one.
naruto is an uzumaki and they are a descendent of the senju, so it could be possible that naruto has water style kekkei genkei, and we already know that narutos affinity is wind that means his affinity is stronger that his kekkei genkei and wind plus water is ice, both his natures are strong so it could be possible that he is an ice style user