On the back, during the early stages of the embryo.
Why can't MPREG writers understand that you need human egg cells to start the development of an embryo?
Read some genetics. They might get it from your grandparents, a distant ancestor, a mutation in your sex cells, or another person you can't tell your spouse about.
Who's more badass: Mafia or Yakuza?
C'mon, it's just biochemistry! You have it in your veins and nerves! Your body knows it, even if you think you know nothing about it.
Why is oil price so damn high today?