Did Joseph Smith teach spirit birth? He says no: http://signaturebookslibrary.org/line-upon-line-11/ He says yes (well, he really says 'maybe'): Go down to the article ‘A CONTINUATION OF THE SEEDS”: JOSEPH SMITH AND SPIRIT BIRTH Brian C. Hales* https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1071&context=mormonhistory The Idea of Pre-existence in the Development of Mormon Thought: (audio and a link to the paper): http://www.exploringmormonthought.com/2018/11/the-idea-of-pre-existence-in.html