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Male hormones are known as androgens. A very important one is called testosterone. 

Males have a pair of sex chromosomes known as XY. The sex of a male is determined at fertilization when a sperm containing a Y chromosome and an egg containing an X chromosome unite. The gonadal sex—what makes someone visually appear to be male—is determined later on, due to the expression of a gene known as SRY.

This gene is located on the Y chromosome and causes undifferentiated gonads to develop along a male plan to form testes. That is because the male hormone testosterone controls the development of male reproductive organs both internally and externally.

The hormone testosterone causes a male at puberty to develop the phenotype associated with males—deeper voice, musculature, body hair, further development of the sex organs—as well as having an effect on the sex drive.

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