AFAIK, a "loan from dad" is frowned upon by the SEC. Something like "insider trading" but I'm not really sure.
That is: If you are related to a person in managment, or related to someone who owns more than 10%, you are "deemed" an insider, IIRC.
OTOH, reading the US Securities laws is a pain in the ass. On page 10 there is an exception which you have to read on page 163, unless they don't obey the requirements of page 42.