Question

how and at what stage is the sex of a child determined​

Answer 1

Explanation:

If you want to determine the sex of a child then it's will be determined by seeing their gene if it's XX then it's female child But if it's XY it's boy but it's very hard to determine . So the easy process is just make him/her naked and check their gamete if you see vagina it's female and if you see anus it's male.

So, it's depend on you that how you determine.