โFor the first few weeks of development, all embryos have both male and female internal reproductive structures, and their external genitalia remains similar for until about 10 weeks gestation. Between 8 and 12 weeks, the baby's internal sex organs start to develop.โ
noting this is a pro life website.
The other website (that was for children), tried to imply that the sex/sex organs determine the moment during fertilization. Thatโs probably a low key anti-trans website.
sigh. :) @Jeber