The issue: They aren't related!
Unlike most of religions, like Islam or Christianity, Jews don't take converts, at least easily, and up to not long ago they hardly married outside their diaspora.
Jews and Arabs were just "that" DNA related before 70 AD, within those nearly 2000 years "Palestinians" were invaded over and over and got waves of immigrants, the Arab population mixed up.

The the other issue: Bible is NOT History, many of those stories at the Bible/Torah were clearly made up or ripped of from some other civilization's legends. Making it hard to know at which point the Jews became actually a people. To not mention the archaeologists set their origin around Ur, in South Iraq.

Still there's an usual confusion with people about "origins". Origins can be somewhat traced if you are of noble origin, if you aren't you can expect to trace back your ancestors at best up to XV Century AD. But this lead to a normal confusion about the names of people and what they mean.
i.e. France got its name after Francs, but it doesn't mean the French population is Franc-descendant, the Franc nobles got lands at France and moved there, but the Franc people didn't pack up and went after nor the nobles replaced the French people, the Francs simply became kings of the local Gauls, obviously some Francs came along, but it's hard to tell how much % of Gaul or Franc a today's French person is, thus mostly will be more Gaul than Franc.
How does this translate to Palestine? We don't know how many migrated from Ur to Jerusalem or if by Jews we are talking about an invading people or a joint of some local tribes with the incoming ones. To which extent then are Palestinian Arabs related to Israeli Jews is way unknown. We just know that between 70 AD and late XIX/early XX Century they hardly had contact with each other.

Still, no doubt that a DNA census would be a good place to start with. But the outcome may make the conflict even worse if the results shows them as unrelated.