The answer is an emphatic Yes, because the Bible specifically teaches this. People (and this includes children) sin because they are sinners. The modern world tries to say people sin because of their environment, but this is contrary to Scripture. The only ones who ever sinned without a sinful nature were Adam and Eve—who also had a perfect environment.
But let’s let the Word itself speak to this issue and answer your question:
David wrote in Psalm 51:5, “Behold, I was brought forth in iniquity, And in sin my mother conceived me.” (NASB). The NIV’s translation is even clearer. “Surely I was sinful at birth, sinful from the time my mother conceived me.”
In Psalm 58:3 David wrote, “Even from birth the wicked go astray; from the womb they are wayward and speak lies.”
Then note Paul’s statement in Eph. 2:1-3, “As for you, you were dead in your transgressions and sins, in which you used to live when you followed the ways of this world and of the ruler of the kingdom of the air, the spirit who is now at work in those who are disobedient. All of us also lived among them at one time, gratifying the cravings of our sinful nature and following its desires and thoughts. Like the rest, we were by nature objects of wrath.” (NIV)
Note two important points here: First, speaking about his readers’ former life (a statement which applies to all of us before salvation) he states they were dead in their transgressions and sins and as a result they followed the ways of the world. Following the sinful ways of the world and the typical lusts patterns of men is the product of spiritual death; the issue of root to fruit. Men sin because they are sinners. Second, he shows this sinful condition and a further consequence, being under the wrath of God, is “by nature,” a condition received by nature, i.e., inherited from our parents, just as David pointed out in Ps. 51:5.
This is further supported by Paul’s statements in Romans 5. Though this passage is dealing with the imputation of Adam’s sin as the federal head of the human race, it also shows us man is sinful because of his relation to Adam.
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—13 for until the Law sin was in the world; but sin is not imputed when there is no law. 14 Nevertheless death reigned from Adam until Moses, even over those who had not sinned in the likeness of the offense of Adam, who is a type of Him who was to come.
15 But the free gift is not like the transgression. For if by the transgression of the one the many died, much more did the grace of God and the gift by the grace of the one Man, Jesus Christ, abound to the many. 16 And the gift is not like that which came through the one who sinned; for on the one hand the judgment arose from one transgression resulting in condemnation, but on the other hand the free gift arose from many transgressions resulting in justification. 17 For if by the transgression of the one, death reigned through the one, much more those who receive the abundance of grace and of the gift of righteousness will reign in life through the One, Jesus Christ. 18 So then as through one transgression there resulted condemnation to all men, even so through one act of righteousness there resulted justification of life to all men.
The point is, after Adam sinned, he and his descendants could only beget sinners, so all men are under the sentence of death, the penalty of sin (see Heb. 7:9-10 for the principle of imputation).
In essence then, all men are behind the eight ball or constituted a sinners for three reasons:
(2) Imputed Sin: They are sinners by imputation; Adam’s sin is imputed to man’s account (Rom. 5:12f) just as Christ’s righteousness is imputed to us when we believe in Christ.
(3) Individual Sin: They are personal sinners; all men sin as individuals since they posses a sinful nature. Even in a godly environment children naturally are selfish and tend to tell lies, etc. (Rom. 3:23).