this might be the dumbest question ever. i do not know the answer so
Why is there no breeding bewteen Throughbreds and Standardbreds?
thanks

If they were DNA compatible, a foal could result but would not be allowed to race as a T'bred & probably not as a S'bred.
Quarter horse mares are bred to T'bred studs & foals are allowed to race but not the opposite.

interesting info here

http://en.wikipedia.org/wiki/Standardbred

 

Thank you for the answers and g'le site. does make sense.