Now, understand that the article took no theological look at the implications of the findings. But, the fact is, we are born into sin.
Romans 5:12 Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned.
Just like green eyes and brown hair, sin is a part of our make-up and has been passed from the first father, Adam. We are born with it. And it starts at the earliest possible age. Also, if you think about it, every one of us was with Adam the day he sinned. What we needed in order to exist was contained within his procreative package. We were not a conscious part of the sin (duh) but were there to experience it. Therefore, we actually participated in it and became sinners. AND, that nature was then passed on to us. So, we are born (and pre-birth) sinners.
For some, this may beg the question of the death of an infant and "the age of accountability." Millard Erickson covers this well in his Systematic Theology. I'll paraphrase his explanation.
We are born with both the propensity to sin and the guilt of that sin. However, the ultimate punishment for the sin (eternal separation from God) is not carried out until we "accept or approve of our corrupt nature." We become condemned sinners once we can understand we are sinners...and like it. Prior to that moment, we have not--and are unable to--acknowledge our sinful nature any more than we are able to accept and acknowledge Christ as Savior at that age. So, the death of a child, while a devastating time, is not a time to worry for her eternity. A couple of scriptures help us here.
2 Samuel 12:23 "But now he has died; why should I fast? Can I bring him back again? I will go to him, but he will not return to me."
David was confident that he would see his dead child again one day. Then later, Jesus said something that allows us to assume children who have died go to heaven.
Matthew 19:14 But Jesus said, "Let the children alone, and do not hinder them from coming to Me; for the kingdom of heaven belongs to such as these."
This would be an odd statement to make if all children who died went to hell. We can safely say that a child, not old enough to choose Christ or sin, is chosen by Christ.
To put the entire post more succinctly, sin is as much a choice as salvation. The problem is, our nature is to choose sin and we must fight against our nature to choose Christ.