Please also keep in mind that Israel have occupied far more land - and promptly given it back as soon as a lasting peace agreement with the country in question was signed (more or less the entire Sinai. And the country who signed a lasting peace treaty and never had trouble with Israel again is Egypt).
Also, please keep in mind that significant more Jews has been chased out of surrounding Arab countries than Arabs from Israel so anyone asking if UN really divided it in a fair way should also have a good case if they weren't up against almost the entire western world, especially academia and journalists who by now have a deep and vested interest in keeping such facts of the table.
Edit: my point in the second paragraph is that I don't think it is fair to demand that Israel retreat from hard-to-attack positions that gives enemies significant advantages (especially Golan) without a lasting peace agreement.
Edit 2: as for Judea and Samaria which constitute a large part of the remaining "occupied territories" they were first captured by Jordan (which was supposed to be the Arab part of the British mandate from the start and which got 70% of the land before the UN resolution which cut the remaining 30% into a Jewish and an Arab part.)
Israel then took it from Jordan in the 1967 war and has been administering it since then.