OK, donning safety armour here but is it not the case that there's no perfect number of children in a family for example:
- one (they might be lonely)
- two (bit of an intense relationship)
- three (someone always left out)
- four (hard for parents to give attention)
My sister had four because she felt we where two intense and she had noone to play with because I had other friends, I have 1 because I started late and was ambivalent about having dc at all.