Rodger,
I think you need to clarify your sowing conditions---do you mean sowing outdoors at cold, soggy times of the year?
I don't think it has anything to do with particular families, or genera....
ANY easy warm germinator does best being sown (and grown) in warm conditions. I have a good collection of members of these families cozy under lights indoors right now and will continue to sow & grow them all winter. They are happy campers.