When a Muslim describes him/herself as 'a descendent of Ishmael', is s/he defining Islam on an ethnic basis?

prophet muhammed(peace be upon him) is a descendent of the prophet isma'al, but not all muslims are descendents from the prophet isma'al( peace be upon him), may be they are reffering to the prophet ( peace be upon him) , though that is wrong , cuz muslims shouldn't make any destinction between the prophets :

Say (O Muslims), "We believe in Allâh and that which has been sent down to us and that which has been sent down to Ibrâhim (Abraham), Ismâ'il (Ishmael), Ishâque (Isaac), Ya'qûb (Jacob), and to Al-Asbât [the twelve sons of Ya'qûb (Jacob)], and that which has been given to Mûsa (Moses) and 'Iesa (Jesus), and that which has been given to the Prophets from their Lord. We make no distinction between any of them, and to Him we have submitted (in Islâm)." 2:136

Any Muslim might say this, in a spiritual sense. However, it is only the Arab nation in particular that is actually descended from Ishmael.

This is accepted by both Jews and Arabs.

The Bible offers some insight into the nature/character of Ishmael, in Genesis 18.

Arabs are not a singular people. Origins are complex and intermingled with many peoples and lines. According to tradition, true Arabs are descendants of Abraham and his son Ishmael and prior to the 20th century, "Arab" designated the Bedouin, tribal-based society of the Arabian desert, which is the birthplace of Arabic. Other Arabs are ethnic groups that have been extant in their lands of origin for millennia. Modern Arab nationalism is a product of 19th- and 20th-century developments and has no prior historical basis. Before the rise of nationalism, most Arabic-speakers identified themselves as members of a particular family or tribe; as residents of a village, town, or region; as Muslims, Christians, or Jews; or as subjects of large political entities such as the Ottoman empire.

What is happening in Bethlehem this year? The following facts were reported:

- In 1967, there were 5 mosques, in 2004 there were 84

- In 1950, Christians were 75% of the population, they are now 12%

- The average age of the Moslem population is 16, that of the Christians - 36

- In the 2005 municipal elections, Hamas won 12 out of 15 seats

- According to Palestinian Authority law, the mayor of Bethlehem must be Christian. His faction has one member only on the council.

Ishmael was the firstborn of Abraham by Hagar, the Egytian slave girl of Sarah and was not the line of the Seed-Messiah--that 'Seed' was through Isaac's descendants, his mother being the free woman, Sarah. Gen. 16:1-4, 11-16.

Matthew 1: 1-16

Luke 3: 23-38

Isaac & Ishmael were both sons of Abraham; they were half-brothers. The descendants of Ishmael were called "Ishmaelites", later they were called "Arabs" because they were nomads. Therefore, Arab Muslims are descendants of Ishmael.

only 20% of Muslims are Arabs

Edit: you are right .. but I live in Egypt and i never heard someone referring to himself as a descendant of Ishmael

Prophet Mohammed was among descendent of Ismael. So, in that we all muslim are spiritual descendent of Ismael not biological.

I am a descendet of Adam,

Peace and have a good day