DH: Parents were originally from a different country, moved to the US when he was young. His name reflects the naming style/trends of whichever country it was - your choice.
DW: Parents were hippies. Her name could be described as nature-ish/unusual/creative.. something along those lines.
For their own children, the couple chose classic - not neccesarily popular or trendy - "American" names.
DS:
DS:
DD:
DD: