Question

Question #a3c0f

Answer 1

Through some randomness and fertilization.

Explanation:

First, know that humans have chromosomes in their body. Males contain XY for their sex chromosomes, while females contain XX for their sex chromosomes. When they have sexual reproduction together, they form gametes (through meiosis), which each contain a random chromosome.

The eggs carry only X chromosomes, as females only contain those. Meanwhile, the sperm can contain either X or a Y chromosomes, as males carry both, so half the sperm have X chromosomes, while the other half contain Y chromosomes.

When they fuse (fertilization), the gender is determined by which chromosome fertilizes the egg. If a X chromosome sperm fertilizes the egg, then a female is born (because XX is made), and if a Y chromosome sperm fertilizes the egg, then a male is born (because XY is made).

Sources:

http://www.bbc.co.uk/schools/gcsebitesize/science/21c_pre_2011/genetics/genesinheritencerev3.shtml

https://socratic.org/questions/how-sex-is-determined-in-humans-by-x-and-y-chromosomes-and-why-males-and-female-