Question

how is the sex of an off spring determined in human beings

Answer 1

There are 23 pairs of chromosomes in females and males.
From these 23 pairs of chromosome 22 pairs of chromosomes are same but 23th pair is different.
In male the 23th pair is XY chromosomes while in female it is XX chromosomes.
If X fuses with Y it is a boy & if X fuses with X it is a girl.

Answer 2

A huamn has 23 pairs of chromosomes along with sex chromosomes A human male has XY chromosomes and female has XX chromosomes.If the sperm containing X chromosme fertilises the ova then female child is born.
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But if the male contains Y and fertilises the ovum then male child is born.