Genesis 4:1 Adam knew his wife Eve intimately, and she conceived and gave birth to Cain. She said, "I have had a male child with the LORD'S help." 2 Then she also gave birth to his brother Abel. (HCSB) Genesis 4: 13 But Cain answered the Lord, "My punishment is too great to bear! 14 Since You are banishing me today from the soil, and I must hide myself from Your presence and become a restless wanderer on the earth, whoever finds me will kill me. (HCSB) Who was he concerned about? Is there any place in the Bible that it specifically says that Cain is First-born child? Did a long time pass before Cain killed his brother, so that his brothers and sisters and their children had already spread out on the Earth? Who, specifically was he concerned about, if it was only his parents? Was he concerned about the future, knowing that his descendents would be killed? If he was concerned about himself, then obviously more children were involved either during Cain's life, before he killed his brother, or he was not the first-born?