Answer:
seven weeks
Step-by-step explanation:
In humans, one single gene is involved in the determination process of whether a human embryo will develop into a male or a female. This gene is called testes determining factor (TDF) and it is located on the Y chromosome. It has been shown that the TDF gene turns on/off a whole set of other genes involved in different signaling pathways, which occurs seven weeks after conception. This master switch in development leads to the formation of the testes that produce testosterone, which is the main masculine hormone.