Genesis 25:12 says, Now these are the generations of Ishmael, Abraham’s son, whom Hagar the Egyptian, Sarah’s handmaid, bare unto Abraham:  We sometimes forget that Ishmael was also the father of many people or nations.  God had made a promise to Hagar, and He kept it.  Verse thirteen states, And these are the names of the sons of Ishmael, by their names, according to their generations: the firstborn of Ishmael, Nebajoth; and Kedar, and Adbeel, and Mibsam,  Verse fourteen continues, And Mishma, and Dumah, and Massa,  And verse fifteen concludes, Hadar, and Tema, Jetur, Naphish, and Kedemah:  Ishmael was also the father of twelve groups of people or nations.  Just because God choses to work through one person or group of people doesn't mean that others a automatically doomed because of where they were born or what group of people they were born into.  What made Abraham and his descendants through Sarah special was not a fact of physical birth, but was the fact of a covenant relationship with God.  As followers of Christ, the same is true of us today.  Verse sixteen says, These are the sons of Ishmael, and these are their names, by their towns, and by their castles; twelve princes according to their nations.  Ishmael's sons prospered in the world.  Verse seventeen declares, And these are the years of the life of Ishmael, an hundred and thirty and seven years: and he gave up the ghost and died; and was gathered unto his people.  Matthew Henry says that it does not say that Ishmael was full of years, so he may have died unexpectedly though he had lived a long life.  We are not guaranteed that we will live a long life, but we need to make each day and year count for God's purpose in our lives to the best of our ability.  Verse eighteen concludes, And they dwelt from Havilah unto Shur, that is before Egypt, as thou goest toward Assyria: and he died in the presence of all his brethren.  The descendants of Ishmael covered a lot of territory.  Verse nineteen declares, And these are the generations of Isaac, Abraham’s son: Abraham begat Isaac:  Now we are given the descendants of Isaac, actually beginning with Isaac himself.  Isaac was the son of promise to Abraham and Sarah.  Verse twenty states, And Isaac was forty years old when he took Rebekah to wife, the daughter of Bethuel the Syrian of Padanaram, the sister to Laban the Syrian.  Isaac was forty years old when Rebekah and he were married.  We are not told how old Rebekah was.  Verse twenty-one declares, And Isaac intreated the LORD for his wife, because she was barren: and the LORD was intreated of him, and Rebekah his wife conceived.  Just like Abraham and Sarah, Rebekah and Isaac had difficulty in conceiving a child, though God had told Abraham that through Isaac he would be the father of a great nation.  Just because God makes a promise to our parents does not mean that everything will be easy for us.  Isaac asked God to give them a child.  He had to have that personal relationship with God and recognize God as being the One Who blessed them with a child.  We must have that personal relationship with God to claim His blessings and cannot be saved by our parents relationship to God.  God answered Isaac's prayer.  Verse twenty-two states, And the children struggled together within her; and she said, If it be so, why am I thus? And she went to inquire of the LORD.  Rebekah was evidently having a difficult pregnancy, and she asked the LORD why this was true.  If we have difficulties in life as followers of Christ, we may wonder why.  The best thing to do is not to doubt God, but to go to Him with our concerns.  Verse twenty-three declares, And the LORD said unto her, Two nations are in thy womb, and two manner of people shall be separated from thy bowels; and the one people shall be stronger than the other people; and the elder shall serve the younger.  God told Rebekah that she was going to have twins, and that the older of the twins would serve the younger.  This was not the normal case, but we need to remember that God is not limited by tradition or man made laws.