Traits like height in humans show continuous variation. How is this possible?

Question

A. The trait is probably influenced by many genes.

B. Hidden variation contributes to variation in height.

C. The environment can influence traits.

D. (a) and (b) above.

E. (a) and (c) above.

Answer 1

E) Complex traits such as height are usually controlled by multiple genes so (a) is true. Environment can also influence phenotype, so (c) is true. For example, in the case of height, nutrition can influence height (which is why the average height in the US is taller than it was a century ago when more people lacked access to adequate nutrition). Genetics and environment are the 2 factors that influence phenotype, so the "hidden variation" referenced in (b) is incorrect.

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