> In particular, don’t found a startup with people that ... have newborn kids As a startup founder with a newborn (well, 14-month-old) I would say that this shouldn't be a global condition. There are plenty like me that I know who can put forth their full commitment - because we have supportive spouses that are completely on board with our entrepreneurial ambitions.
I wouldn't found a startup with no income and looking to leverage that success early or your family will starve. If you have an adequate enough padding though, and yes a supportive family, you can easily be solo.