Child of a single parent
I and my 2 siblings are children of a single mum, and while we turned out fine (all tertiary trained and in good jobs) my mum pretty much killed herself to get us where we are. I concur that while effective single parenting is quite possible, having two parents is definitely an advantage.
Main reason I am childless is I never managed to find someone to be a co-parent with me.
Any monkey or mouse can reproduce, /parenting/ takes time and effort - plenty of men and women that think they want to have kids just aren't up to it.