Is there any truth that 80% of Palestinian's come from the same bloodline as Jews?
No
Palestinians are what ancient texts refer to as "The Philistine's" obviously well known in the Biblical Narrative. Many ancient texts (non-Biblical) spoke of these people as a race of warriors, far superior then their ancient neighbors.
During the reign of Ramses the 2nd, well over 3000 years ago the Canaanites where constantly in battle with Hebrew tribes, not Israelis but other Hebrew tribes. Now the Philistines were Hamitic tribes and The Hebrew tribes where Semitic tribes, so this was where the hatred stemmed from. The Philistines where living in Canaan (modern day Israel) so they where incorporated among the Canaanites but they did not fight the Hebrews because the Philistines where Semitic and at this point in time Semitic people did not fight each other.
Once most Hebrew tribes where completely obliterated by the Canaanites they established complete control and supremacy in that region until The Israelite came in and took over the land and wiped the Canaanites out and Established an Empire there. One generation later the Empire grew under The Davidic Dynasty and of course David's son Solomon who is famous world wide for his wisdom, wealth, and for building The Temple in Jerusalem.
During this period is when the first wars erupted among The Philistines and The Israelite and has been going on back and fourth for over 3000 years. What is very interesting about The Israeli's and the Philistines is that they were both separated from their original people of whom they belonged too.
The Israeli's were Hebrews but did not take part in Hebrew conquest or warfare as they wanted their own Race, which is The Israelite.
On the flip side The Philistines were Canaanites but did not take part in Canaanite Conquest or Warfare as they wanted their own race as well which is The Philistines, modern day Palestinians.
Now Palestinians remain to be the only known tribe that survived under Canaanite Union, so they are the only Canaanites left on the planet but of course no Palestinian likes to be called a Canaanite.
As for The Hebrews, many got wiped out but several Hebrew descendants are still around; The Israelite of course. The Arabs are also Hebrews, all of them and of course they definitely do not like to be called Hebrews. The Jordanians are also Hebrews. Some Europeans are also Hebrew, however many argue this because so much information is lost, so it is hard to tell. One theory is that the Edomites (a Hebrew tribe) eventually made it to Europe, the main evidence for this is that the Edomites where the first to use the term "Dukes" and of course we know Great Britain and several surrounding areas use this term "Duke" but definitely a Hebrew term.
Some believe The British people are descendents of the Edomite which would make Britain and Israel cousins but again it is very difficult to establish this claim