WLC - Question 26 How is original sin conveyed from our first parents unto their posterity?
WLC - Answer 26 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.
WLC - Answer 26 (Bob) 'Universal sin' is conveyed by natural generation, being born as an animal wanting of knowledge of God, unable to choose to love of it's own accord. Though born in ignorance of God, they are not culpable of sin, since where there is no law, there is no judgement of the law.