Male or Female? This Is Decided Before You’re Born

So the external sexual organs of males and females originate from the same basic tissues. That's why we have stitches mark extending from the scrotum up to the penis shaft as skin getting closed if boy developing in fetus and in case of girl it getting wider as for vaginal opening.. It’s truly an example of how nature carefully shapes development in different ways.

Sex is determined at fertilization (XX or XY), and external genitalia differentiate during early fetal development under hormonal influence—clearly visible by around 18–20 weeks.

Dios jugándome una pequeña broma:

Oh, it turns out that reversing gender bend is possible.

Exactly