One bit of proof: Two male black swans will get together and will also adopt abandoned baby swans.

This one fact is fun💪

Yeah this is the evolutionist version

God made these species.

its not "unnatural" but it is a developed personality/preference/prejudice
so no its not unnatural as to say as every human should be 'natural' (like as to how unnatural is used as meaning a homophobic person)
its just personality and hatred manifesting like everyone else does