Cain was not created in Adam in the beginning ! When scripture gives us the generation of Adam, it does not include cain in the genealogy, simply because he was not originally part of that seed of mankind, created in Adam ! Lets read scripture here Gen 5:1-32 This is the book of the generations of Adam. In the day that God created man, in the likeness of God made he him; 2 Male and female created he them; and blessed them, and called their name Adam, in the day when they were created. 3 And Adam lived an hundred and thirty years, and begat a son in his own likeness, and after his image; and called his name Seth: Note: Seth was a replacement for Abel whom cain murdered Gen 4:25-26 25 And Adam knew his wife again; and she bare a son, and called his name Seth: For God, said she, hath appointed me another seed instead of Abel, whom Cain slew. 26 And to Seth, to him also there was born a son; and he called his name Enos: then began men to call upon the name of the Lord. 4 And the days of Adam after he had begotten Seth were eight hundred years: and he begat sons and daughters: 5 And all the days that Adam lived were nine hundred and thirty years: and he died. 6 And Seth lived an hundred and five years, and begat Enos: 7 And Seth lived after he begat Enos eight hundred and seven years, and begat sons and daughters: 8 And all the days of Seth were nine hundred and twelve years: and he died. 9 And Enos lived ninety years, and begat Cainan: 10 And Enos lived after he begat Cainan eight hundred and fifteen years, and begat sons and daughters: 11 And all the days of Enos were nine hundred and five years: and he died. 12 And Cainan lived seventy years and begat Mahalaleel: 13 And Cainan lived after he begat Mahalaleel eight hundred and forty years, and begat sons and daughters: 14 And all the days of Cainan were nine hundred and ten years: and he died. 15 And Mahalaleel lived sixty and five years, and begat Jared: 16 And Mahalaleel lived after he begat Jared eight hundred and thirty years, and begat sons and daughters: 17 And all the days of Mahalaleel were eight hundred ninety and five years: and he died. 18 And Jared lived an hundred sixty and two years, and he begat Enoch: 19 And Jared lived after he begat Enoch eight hundred years, and begat sons and daughters: 20 And all the days of Jared were nine hundred sixty and two years: and he died. 21 And Enoch lived sixty and five years, and begat Methuselah: 22 And Enoch walked with God after he begat Methuselah three hundred years, and begat sons and daughters: 23 And all the days of Enoch were three hundred sixty and five years: 24 And Enoch walked with God: and he was not; for God took him. 25 And Methuselah lived an hundred eighty and seven years, and begat Lamech. 26 And Methuselah lived after he begat Lamech seven hundred eighty and two years, and begat sons and daughters: 27 And all the days of Methuselah were nine hundred sixty and nine years: and he died. 28 And Lamech lived an hundred eighty and two years, and begat a son: 29 And he called his name Noah, saying, This same shall comfort us concerning our work and toil of our hands, because of the ground which the Lord hath cursed. 30 And Lamech lived after he begat Noah five hundred ninety and five years, and begat sons and daughters: 31 And all the days of Lamech were seven hundred seventy and seven years: and he died. 32 And Noah was five hundred years old: and Noah begat Shem, Ham, and Japheth. Notice, it was these who were out of that generation which God had created in Adam, when He created him in the likeness of God as per Gen 5:1-2 ! Also if we read the genealogy of Christ as written in Lk 3:23-38, notice no mention of Adam's firstborn cain ! Again, that is because cain was not in Adam when man was created in the image of God in the beginning ! Later scripture tells us why this is so ! Because cain was out of that wicked one 1 Jn 3:12 12 Not as Cain, who was of that wicked one, and slew his brother. And wherefore slew he him? Because his own works were evil, and his brother's righteous. Cain was of that wicked one , the devil, who was sown by him as Jesus makes clear here Matt 13:36-39 36 Then Jesus sent the multitude away, and went into the house: and his disciples came unto him, saying, Declare unto us the parable of the tares of the field. 37 He answered and said unto them, He that soweth the good seed is the Son of man; Adam and his generations in the beginning is the good seed Gen 5:1-2 38 The field is the world; the good seed are the children of the kingdom; but the tares are the children of the wicked one; The tares are those of the serpents seed as per Gen 3:15-16 39 The enemy that sowed them is the devil; the harvest is the end of the world; and the reapers are the angels. Cain was out of that generation, and not out of that Generation in Adam !