The Arabs and original Jews (Hebrews) are semitic peoples who descend from Abraham through his sons Ishmael & Isaac. Not all Jewish people today are of Hebrew descent so not all Jews and Arabs are related though a great many of the are.

I think a better question would be are Hebrews and Arabs related. And your answer is yes. Abraham (who was promised that all of the prophets will be his sons by god), had two kids, Isaac and Ismael, The Hebrews descended from Isaac and the Arabs descended from Ismael. There were a lot of prophets of Isaac's side and there were only four on Ismael's side. God kept his promise to Abraham, and all of the prophets god sent including Mohammad was from Abraham's side. But to answer the question yes, Jews and Arabs are distant cousins, but this only works for the Jews in Israel for that matter (some non-Jews converted to Judaism doesn't make them distant cousins). The Hebrew Jews would have the same DNA tests as the Arabs mainly because they both had the same father-Abraham.