Hi Mocnarf... :-)
I too have wonder why Joseph didn't have more children.
A few ideas... first, if a guy is married (legally), and is having several secret affairs, he is most likely not able to be with the other women every single night. Lets say he visits one extra woman a week, (assuming he is having a normal relationship with his actual wife). OK, so lets say there are only ten extra woman rather than the 30-40 Joseph Smith had. That would mean he is visiting each of the ten women only once every three months or so. Unnlikely he would catch them at the right time.
Secondly, people were not stupid. If it was not in the best interest of Joseph Smith to have children, they had available to them, several forms of birth control that while not completely effective would decrease the likelihood of impregnation.
There are any children recorded by any of his other wives are there?
Well... my guess is yes. Some DNA tests have been run, but as I predicted, we would only hear of results that showed those who were NOT Joseph Smith's descendants. In addition, last I heard there were some who were likely to be descendants who were not tested. Finally, there are those who believe they are descendants of Joseph Smith, alive today.
Not all sexual activity is necessarily vaginal.... Could it be Joseph liked the kind of sex that Emma was unwilling to give?
Why would you assume Emma was unwilling to "give" various forms of sex? The fact that men can engage in various sexual activity does not suggest Emma was unwilling to engage in these activities.
~dancer~