Is it true Karl Marx had Jewish ancestry, if so does this mean Marxist theory was designed by the Jews?

Does it make any difference?  Your question smacks of anti-Semitism.  Perhaps you should pay more attention to the foundation of Marxism and compare and contrast it to successful economic and political theories rather than trying to assign blame. 

You realize this is why Hitler hated socialism, right? You haven't cracked some kind of code, kiddo.

Marx did not identify as a Jew, regardless of his ancestors. So, no, that leap cannot be made.

it was designed buy a therapist, Marx