The solution is clearly to use modern genetics to discern which genes dominated the regions since prehistory and then appropriately segregate the world based on historical and genetic analysis. Genes are fairly easy to track and it is obvious which genes are Palestinian Jewish genes and which genes are Palestinian Palestinian genes.
We should complement this endeavor clearly by studying factual and non-biased historical texts, like the Bible and the Quran, in making our judgements.
Of course, we will also need to torture language to achieve our propagandistic goals. Knowledge is ignorance, war is peace and jews are antisemites.