Everyone should know how human reproduction works.
In some discussions here and on other forums I have noticed that some people do not really understand exactly how babies are made beyond sex can = pregnancy which can = having a baby.
Some women do not know that it takes MANY, MANY sperm to cause a pregnancy.
Some women do not know that a very large number* of embryos die before the first trimester.
*as many as 70%
What are some things you have noticed that some people do not understand?