Meet the Cohens: Natasha (right), a 23-year-old Ukrainian with her Samaritan father-in-law, Yousef Cohen (left), at his West Bank home

The descendants of the Good Samaritan are not only alive and well in the Holy Land, but are also on a quest for love. Finding a partner is difficult in a community of fewer than 800 members, all of whom are blood relations. With genetic diseases threatening their future, Samaritans are, for the first time in their long history, marrying outside the community. Which is how Natasha, 23, from Nikolaevskaya Oblast in Ukraine found herself perched on a holy mountain in the West Bank and following the religious laws of one of the smallest ethnic communities in the world.

"Talk of family and old descent!" exclaimed Mark Twain in The Innocents Abroad after his first encounter with the Samaritans in the Holy Land back in the 19th century. "Princes and nobles pride themselves upon lineages they can trace back some hundreds of years." All this, wrote Twain, was a mere "trifle" compared to the Samaritans "who can name their fathers straight back without a flaw" for thousands of years, while others "grow dazed and bewildered when they try to comprehend it!"

Twain was not exaggerating. Sitting in a large stone house in Kfar Luza, on Mount Gerizim in the West Bank, the community elders tell me without a blink that they can trace their family trees directly back to Moses himself. According to them, Moses's brother Aaron was the first Samaritan high priest.

Academic scholars are at a loss to determine the exact origins of the community. Abraham Tal, an expert in Samaritan Aramaic language at Tel Aviv University, told the Israeli newspaper Haaretz that many scholars believe the Samaritans to be "a sect that diverged from Judaism around the time of the Second Temple". Tal added: "What is sure is that they are mentioned by the historian Flavius Josephus" who wrote during the 1st century AD.

Today the 133rd high priest leads the faithful on Mount Gerizim, a hilltop deemed by the Samaritans to be their holiest site. But with ancient status come centuries-old tensions with other faiths. The dispute with Judaism dates back to the Old Testament. The Samaritans claim that the "legitimate" blood line of high priests stayed on Mount Gerizim while the "false" line ended up in Jerusalem.

The dispute is also mentioned in the New Testament. When Jesus meets a Samaritan woman at Jacob's Well, just a few kilometres away from Mount Gerizim, she does not hesitate to take the bull by the horns: "Our ancestors worshipped on this mountain," she tells Jesus, "but you Jews claim that the place where we must worship is in Jerusalem." (John 4: 5-20.)

In the end Jesus succeeds in converting the Samaritan woman. On the ground, a cold war of ideologies continued.

To rival the Jewish Holy Temple, the Samaritans built their own on Mount Gerizim. Both were eventually destroyed. One of the reasons why the Samaritans hold Gerizim as sacred is because they say Moses ordered them to protect it. This decree is not mere hearsay, they say, but is enshrined in the Samaritan Ten Commandments, markedly different to the Jewish and Christian version. The Samaritans also believe it was on Mount Gerizim that Abraham was ready to sacrifice his son, dismissing the Temple Mount, where Christians, Jews and Muslims say it happened. When Samaritans pray, they always face Gerizim.

To this day, the Samaritans stick to the letter of the Old Testament, following ancient biblical rituals. While Jews celebrate Passover  with the traditional rituals of Seder night, the Samaritans gather chanting in ancient Hebrew and Aramaic atop their holy mountain and proceed to slaughter dozens of lambs. While Jews dip their fingers in a glass of red wine, the Samaritans dip theirs in the blood of the lamb, place a dot of it on their faces and then barbecue the meat on a giant bonfire by the light of the full moon.