Answer: Original sin is conveyed from our first parents unto their posterity by natural generation, so as all that proceed from them in that way are conceived and born in sin.₁

1. Psalm 51:5; Job 14:4; Job 15:14; John 3:6

For further study see:

1. WSC 14:  What is sin?
2. WSC 15: What was the sin whereby our first parents fell from the estate wherein they were created?
3. WSC 18: Wherein consists the sinfulness of that estate whereinto man fell?
4. WSC 20: Did God leave all mankind to perish in the estate of sin and misery?
5. WSC 84: What doth every sin deserve?
6. WSC 85: What doth God require of us, that we may escape his wrath and curse due to us for sin?
7. WLC 24: What is sin?
8. WLC 25: Wherein consists the sinfulness of that estate whereinto man fell?
9. WLC 26: How is original sin conveyed from our first parents unto their posterity?
10. WCF CHAPTER 6: Of the Fall of Man, of Sin, and of the Punishment Thereof