Комментарий к Берешит 10:14

ואת פתרסים ואת כסלחים אשר יצאו משם פלשתים AND PATHRUSIM AND CASLUHIM OUT OF WHOM CAME PHILISTIM — They (the Philistines) were descended from both of them for the Pathrusim and the Casluhim used to live together in promiscuous intercourse, and the Philistines were their offspring (Genesis Rabbah 37:5).

ואת...אשר יצאו משם פלשתים, it is not clear if the Philistines are the offspring of only the Kassluchim or from both the Patrussim and the Kassluchim who had intermarried among themselves so that the Philistines had genetic input from both these families. It is interesting that the expression שם or משם, i.e. expressions used to describe physical locations, origins, are also used elsewhere in a genetic sense such as in Genesis 49,24 משם רועה אבן ישראל, “from there he became the shepherd of Israel.”

ואת פתרוסים ואת כסלוחים אשר יצאו משם פלשתים, “and the Pathrusim and the Casluhim, whence the Philistines came forth.” The Torah stresses this in order to tell us that the nation of the Philistines have their origin in bastardy The two above-mentioned nations engaged in wife-swapping and the Philistines emerged as a result of this incest (compare Bereshit Rabbah 37,5). You will find that all these descendants of Mitzrayim have names which end with the letters ים, “sea,” an allusion to their eventual demise in the sea (Pessikta Zutrata). The first of these nations was called לודים, since they were both born in the sea and drowned in the sea.

And the Plishtim descended from them. For if the Plishtim descended from the Kasluchim alone, it should say: “And the Kasluchim produced the Plishtim,” and omit, “From whom came.” Furthermore, Scripture cannot be identifying which Kasluchim it speaks of — i.e., they are the ones from which the Plishtim came — as no other mention of Kasluchim appears in Scripture. (Nachalas Yaakov)

כפתרים, according to Rav Saadyah gaon, a tribe that used to live in the neighbourhood of Port Said in Eastern Egypt. The reason they are mentioned here separately is that although the Philistines, basically, are descended from the offspring of מצרים, the land of Egypt did not belong to them, so that the Israelites were entitled to take over the parts of the land of Canaan then inhabited by the Philistines.