Polygenic traits are controlled by:

The correct answer is Option (3) → Three or more genes

Polygenic traits, such as human skin colour and height, show a range of forms rather than two clear types. They are controlled by three or more genes, each adding a little to the trait, and the environment also has an effect.

Option (1) One gene — Incorrect. One gene gives clear-cut forms, like Mendel’s purple and white flowers.

Option (2) Two genes — Incorrect. Two genes are too few for the smooth range seen in polygenic traits.

Option (3) Three or more genes — Correct. Polygenic traits are controlled by three or more genes, each adding a little to the effect, and the environment also influences them. Human skin colour is an example.

Option (4) One or two genes — Incorrect. One or two genes give a few clear-cut forms, not the smooth range seen in polygenic traits. The book says polygenic traits are controlled by three or more genes.

NCERT Extract:
Polygenic Inheritance – …