Nowhere ever does the bible define sin as something inherited thru genes of DNA that is passed one from another. Nowhere does the bile ever say sin is a substance as bacteria that is transmitted one to another no does the bible ever define sin simply as an idea that is passed one from another. Original sin therefore cannot possibly be biblical for sin does not exist until a transgression occurs and each person is responsible for his/her own choice in choosing to commit transgressions and not another person transgression.
When you extend an argument to the rediculous, "Sin is something inherited through genes of DNA," or, "Sin is a substance transmitted as bacteria," and then attack the rediculousness (of your own making) this approach to argument is known as a straw man logical fallacy.
Now it is easy to gain rhetorical points by deploying these types of fallacies given that A: Your audience is unfamiliar with scripture (which doesn't seem like a good assumption), and B: Your audience is unfamiliar with logic and logical fallacy, (which again doesn't seem like a good assumption).
Now original sin was a concept discussed since the beginning of the epistles. We can argue as to its truth-value but let's not misrepresent the claims of scripture with straw men.
Psalm 51:5 states that we all come into the world as sinners: “Behold, I was brought forth in iniquity, and in sin my mother conceived me.” Ephesians 2:2says that all people who are not in Christ are “sons of disobedience.” Ephesians 2:3 also establishes this, saying that we are all “by nature children of wrath.” If we are all “by nature children of wrath,” it can only be because we are all by nature sinners — for God does not direct His wrath towards those who are not guilty. God did not create the human race sinful, but upright. But we fell into sin and became sinful due to the sin of Adam.
Scripture speaks of humans as unrighteous from infancy
There are also verses which declare that we are all unrighteous from the time that we are born. Proverbs 22:15 says “Foolishness is bound up in the heart of a child.” Genesis 8:21 declares, “. . . the intent of man’s heart is evil from his youth.” Jonathan Edwards, in his classic work The Great Christian Doctrine of Original Sin Defended, remarks that on this verse: “The word translated youth, signifies the whole of the former part of the age of man, which commences from the beginning of life. The word in its derivation, has reference to the birth or beginning of existence . . . so that the word here translated youth, comprehends not only what we in English most commonly call the time of youth, but also childhood and infancy.”
A lot more work has to be done by you and others to demonstrated that dozens of passages in both Old and New Testaments were exegeted improperly. And church fathers both ante and post-nicene, were mistaken. Catholicism and Protestantism in the main have missed the meaning as well. I am willing to engage the evidence but mountains have to be moved here.
Yes.. babies are not righteous in anyway what so ever. Blind...yes. Well Jesus said..if you were blind you would have no sin. you say you see your sin remains. We all were born into sin. There is no way around this. So a baby is blind so to speak till some point..yet.. this can be till your very old.. I mean.. how many people in this world NEVER heard of Jesus.. cant be held to answer for something they never heard of.. so blind they are.. 
