My religious friends were shocked because I know where the vagina is located

The other day they asked me about how some positions worked (eg doggy) so I told them the penis goes there because the vagina is right there and the male does such and the female does such but then they freaked out because I'm 'not supposed to know these things'.

Now I myself am a little religious and have never watched porn but knowing the general location of the vagina is the least you can do as a 17 year old who has taken biology classes for several years. Knowing the human anatomy isn't a sin, women are not aliens.