Reading a recent article caused me to reflect on a memory buried deep in my childhood that caused a few doubts or concerns about Mormonism: what am I supposed to think regarding “gender [as] an essential characteristic of individual premortal, mortal, and eternal identity and purpose” (Family: A Proclamation to the World) when more than two sexes exist? At the time, I wasn’t too familiar with intersexism (atypical combinations of physical features that usually distinguish female from male) but was remotely aware that things aren’t always clear. I shared this doubt with someone who explained to me that the prophets and apostles of our church have said it is impossible for a male spirit to be born into a female body (and vice versa)–God would never allow/do that to someone. It explained nothing about people who feel they are born the wrong gender and it didn’t explain how intersex individuals fit into God’s plan.
The plan of salvation according to LDS theology
Here’s the article I read. It’s a really good read and raised important questions about gender and theology within the LDS Church. Eternal Gender?
unambiguous 
The spirit world looks like sperm.
As sperm now is, you once were; as you now are, sperm may become.