Answer: Environmental conditions, such as temperature and availability of nutrients can affect phenotypes. For example, temperature affects coat color in Siamese cats. ... Height in humans is a complex phenotype influenced by many genes, but it is also influenced by nutrition
Some mutations don't have any noticeable effect on the phenotype of an organism. This can happen in many situations: perhaps the mutation occurs in a stretch of DNA with no function, or perhaps the mutation occurs in a protein-coding region but ends up not affecting the amino acid sequence of the protein.
