It is, perhaps, noteworthy that modern Hebrew does not have any indigenous swear-words. Practically all swear words and phrases in Hebrew are, in fact, borrowed from other languages (usually either Arabic, Russian, Yiddish or English). This does not mean that the imported words always retain their original meaning or connotation (most people don't know, for instance, that the common manyak is a derivation of the Arab manyuk or that this word originally meant 'someone-who-takes-it-up-the-arse'), but they are usually recognizable to those who speak the original lanuages from which they were taken. This can lead to embarrassing situation, because when an Israeli says kibini mat he doesn't really think of the Russian 'Go to your fucking mother'*.

What brought this situation about was the fact of the unusual and unique history of the Hebrew language. Hebrew is the only language in recorded history to be brought back to life as a spoken language. Ever since the 5th century CE, there were no Hebrew native speakers. As jews were dispersed throughout the world they have come to adopt local languages, often modifying them a bit to better suit their needs (thus creating the many "Jewish Languages"), forsaking in the process their own language. Even in Israel itself, with the exception of the area surrounding Jerusalem, Hebrew was replaced with Aramaic as spoken language as early as the 1st century BCE.

Hebrew has continued to be a written language and has accumulated over the centuries a large, diverse and rich academic literature, rivalled only by the Latin one in Europe, and exceeded (at that time) only by the Arabic one. However, diverse though this literature was, its main concerns were science, history, theology, philosophy, poetry and explorations, fields not notorious for using much dirty talking.

When the efforts to revive Hebrew started (around the late 19th century), the task of adapting the language to everyday speech was in the hands of scholars, and their main concern was not the creation of curses (not to mention they probably thought it unseemly). However, people coming to Israel from the diaspora needed such words, and when they couldn't find ones in the old-new language, they reverted to their native tongues (mostly Russian and Yiddish), or borrowed from the other inhabitants of the land (Arabs).

The infiltration of English words into Hebrew is a relatively new occurrence (a matter of the last two or three decades), aided mainly by cinema and television (and, probably, the lack of local words).

* thanks to Footprints for correcting the mistaken translation I supplied earlier.