if an animal has both sexes how do they not mate with themselves?

Question: if an animal has both sexes how do they not mate with themselves?
- Keywords:
  animal,
  mate,
  sex
Asked by emeraldtail to sakshisharda on 15 Mar 2018.
- Sakshi Sharda answered on 15 Mar 2018:
  
  That’s a very thoughtful question and guess what they do 🙂 for instance snails have both sexes and they reproduce by mating with themselves. this means that the female parts of the snail mates with the male parts. So cool right? 🙂

Question: if an animal has both sexes how do they not mate with themselves?