This question and variants like it have arisen in the past. Follow this reasoning:

Basis: Jesus was sinless (Hebrews 4:15, 1 John 3:5). Jesus was a descendant of Adam as per Luke 3 (in His humanity). Descendants of Adam receive original sin because they were in Adam when Adam sinned (Romans 5:12). So how did Jesus avoid having original sin?

There are several popular responses to this (basic arguments given below) that show there is no contradiction within Scripture:

1. Father’s line: Jesus inherited genetic material from Mary (to be fully human, i.e., descendant of Adam to become the Last Adam) but not from Joseph, therefore, original sin must pass through the father to the offspring. This allows Jesus to avoid original sin.
2. Sin nature is not sin: the terms “sin nature” or “original sin” are not found in the Bible and are terms derived by humans when looking at certain passages. Sin nature is a tendency toward sin, not sin in and of itself. This avoids Jesus being a sinner.
3. Sin nature passes spiritually: original sin is nonmaterial and doesn’t need to pass along to offspring via genetics. It is passed along spiritually by virtue that all are descendants of Adam. But God withheld original sin from entering Christ in the womb.

“Father’s line” model

The first view is the Father’s line model. Initially this sounds like a reasonable model but there are some problems associated with it.

There are no Scriptures that connect the virgin birth to sin or sin nature. The reason for the virgin birth is a miraculous entrance into the world by fulfilling prophecies such as Genesis 3:15 and Isaiah 7:14. Caution should be exercised when adding other implications to the virgin birth.

Second, if sin nature is materialistic and passed through the father while reproduction occurs, then, in theory, a “clone” (of sorts anyway) using two sets of female DNA (resulting in only a female) could be sinless and Jesus would no longer be unique as being separate from sinners (Hebrews 7:26).

The punishment for sin is death (Genesis 2:17; 3:19, Romans 5:12) and theoretically if one of these “clones” was without sin nature and didn’t sin, then they could not die and should live eternally, hence, a means of eternal life without the need for Jesus Christ (John 14:6). Jesus, who was sinless still died on the cross without being a sinner; but in order to die, He became sin for us (Hebrews 9:28; 2 Corinthians 5:21).

Often in today’s culture people try to find materialistic explanations due to influences of materialism and naturalism (foundations of evolution) which exclude supernaturalism and the spiritual realm. But truth, logic, information, souls, mind, sin nature, and so on are not material entities.

It is vital to realize the difference between the material and the immaterial in this discussion. Consider the following:

1. Adam

   Adam originally had perfect DNA¹ (Genesis 1:31, Deuteronomy 32:4), and yet there was no original sin found in him at the start. Sin nature came about when Adam sinned. Were genetic changes involved in Genesis 3? Perhaps, but such a position should not be held dogmatically. But the fact that genes can exist without sin nature, shows that sin nature is not intrinsically bound to genetics.

2. Life is passed along and it is non-material

   Life also passed from Adam to all of us. But originally Adam’s life came from God when God breathed life into him (Genesis 2:7), even though his entire body was formed with DNA, flesh, bones, etc. This immaterial life from God was independent of Adam’s body, since it was “breathed”into it.

3. Satan/Demons

   Satan and demons may be the pinnacle to show that sin nature is not bound to material means. Satan is spirit and he can tempt, influence, and even enter into people (Luke 22:3 with Judas) or animals (Genesis 3 with the serpent, and in Mark 5:1–17 with Legion and the swine). They have sinned and continue to sin (having their own sin nature) without human genes. This shows that sin nature is not confined to human DNA.

“Sin nature is not sin” model

Instead of avoiding sin nature, this model teaches that sin nature is not sin in and of itself but the tendency toward sin and Jesus, even with this tendency, did not sin. In part, this model derives from Hebrews 4:15, meaning that Jesus had to have a sin nature in order to be tempted just as we are. In other words, the model teaches that one can be justified in sinning because “man couldn’t help it” and therefore cannot rightly be compared to Jesus who wouldn’t have undergone what the rest of us underwent. This model also assumes the peccability of Christ, which is hotly debated.²

Hebrews 4:15
For we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin.
 

Obviously, Jesus was tempted externally, having fasted 40 days and nights, and then Satan himself tempted him three times (Matthew 4).

Jesus was tempted internally as well if one looks at the Garden of Gethsemane (Matthew 26:39, 42, 44). Jesus in His humanity was “tempted” to give up the cup that had been passed to Him, but still remained within the will of God, not His human will. Another case that reveals Christ’s internal temptations is Hebrews 2:18 which says:

For in that He Himself has suffered, being tempted, He is able to aid those who are tempted.

Christ was suffering due to temptation. Also take note of Paul’s comment:

1 Corinthians 10:13
No temptation has overtaken you except such as is common to man; but God is faithful, who will not allow you to be tempted beyond what you are able, but with the temptation will also make the way of escape, that you may be able to bear it.
 

If God doesn’t permit one to be tempted more than one can bear, and Christ—our perfect example and God incarnate—was tempted to an extreme that we have not had to bear. A temptation, in and of itself, is not sin. Temptation may lead to sin, and here is the progression described in James.

James 1:14–15
But each one is tempted when he is drawn away by his own desires and enticed. Then, when desire has conceived, it gives birth to sin; and sin, when it is full-grown, brings forth death.
 

Note in the progression that being drawn away by our own human desires and enticed is also not sin. When desires conceive or are put into action or even thought (Matthew 5:28), then it becomes sin. When look at Genesis 3, we find this progression with the Woman, Eve:

1. Tempted by the serpent
2. Drawn away and enticed by desiring the fruit
3. Desire conceived when she ate, thus her action of sin.

Of course, Adam was the representative for humankind, and when he ate, all humanity became doomed to the Curse. Turning to Matthew 4 in the Garden of Gethsemane, Jesus was perhaps enticed by the desire of not fulfilling what He was there to do. And yet, this desire did not conceive and Jesus did not sin.

Does this mean Jesus had original sin then? This second view points out that “original sin” and “sin nature” are phrases that are not found in Scripture, but are derived from Genesis 3 and summed up in Romans 5 (verse 12 specifically), elaborated on in Romans 7:13–25, and, by common definition, means the tendency toward sin as a consequence for descendants of Adam because of his sin. But in the same respect, all have become sinners as a result (Romans 3:23, 5:19).

Original sin means having an indirect part in Adam’s sin and thus tending toward sin. In this model, Adam was the responsible party and died for his sin. We are not responsible for that sin but for the sins we commit ourselves. John 8:24 gives an indication that people die for their own sins, not necessarily the sin nature that was inherent from Adam. This sin nature then is not sin itself, but explains why mankind sins and tends toward it.

Having a part of Christ being directly given to Mary from God—the Holy Spirit, shows that Christ is both fully God and fully human (Colossians 1:16, 2:9; John 1:1–3; Hebrews 2:14). In one sense, it excused Jesus for not being in Adam when he sinned but since His life also came through Mary, it goes back to Adam as well.

The model also teaches that since Christ has direct lineage to Adam through Mary, this shows that He inherits this nature in His humanity, and since He was without sin, then sin nature cannot be sin but merely the tendency toward sin or in other words, to overtly make desires conceive into sin. The judgment of Revelation 20:11–15 also supports this notion since the people there are judged “according to their works” (vss. 12 and 13) as opposed to being judged for their nature. So from the moment of fertilization, people’s desires conceive into sin. Yet, Christ’s desires never turned to sin.

Scripture never records if Satan ever tried to tempt God the Father, but would seem unlikely since He cannot be tempted (James 1:13), but he did tempt Jesus. In Christ’s humanity, Satan had an opportunity to tempt Christ; yet Christ did not succumb.

Christians, although having sin nature, do not continually sin (1 John 3:9). Therefore, they can resist sin, even though sin nature has reign over them. Consider Adam and Christ. Adam sinned without sin nature, and yet Jesus did not sin, having such a nature in this model.

One problematic issue in this model comes down to the interpretation of original sin. If one was in Adam when Adam sinned, then he is a sinner because Adam sinned. So although this model downplays that mankind was involved in Adam’s sin, it doesn’t completely remove it.

Another objection relates to an internal temptation of Christ. Never once did Satan enter into Christ, for he cannot. So any alleged internal temptation of Christ must come from Himself. A desire to rebel against God is needed to conceive into sin and Christ has no such desire in Himself. Recall, that James 1:13 says that God cannot be tempted, and Jesus being the Creator God (John 1, Colossians 1, and Hebrews 1) cannot be tempted internally, i.e., He cannot desire to rebel against God, i.e., Himself. This is different from someone trying to tempt Him. Christ’s own desires would not lead Him toward rebellion against God. This makes sense because there are both righteous desires and evil desires.

So why was Jesus in anguish in the Garden of Gethsemane? In addition to the anguish of the terrible experience He was about to face, it was morally wrong for Him to be crucified. One possible reason Christ felt torn was because it was wrong to punish the sinless with death (i.e., Himself), yet it had to be done for love and salvation of mankind as an atoning sacrifice. Any desires of Christ in the Garden of Gethsemane could not have been anything but a righteous desire (Hebrews 12:2)—death should not be the punishment for the Son of God, but had to be done for grace. Christ was not tempted internally to sin but the desire to do two different “right” things. So this second model fails on several counts.

“Sin nature passes spiritually” model

Unlike the first model, this third model does not limit sin nature to a physical entity that needs to be passed down. Hence there is no problem for sin natures in Satan and demons. This model assumes that original sin is sin, unlike the previous model.

This model takes the position that original sin is not required for one to be tempted in every way. It goes back to the Woman in the Garden of Eden and points out the temptations prior to original sin. When we look at Adam and the Woman, we find that a person can exist without sin nature and still be tempted both externally and internally (the Woman desiring the fruit and taking it), but then sinning by following through when she and Adam ate.

Therefore, when Christ was conceived by the Holy Spirit, there was no intrinsic original sin passed to Christ, while still using Mary’s genetic material³ to become a descendant of Adam. Such a task would be no problem for the Creator of the universe.

To summarize, this view holds that sin nature is not physical and, thus, not passed along by genetic means but by spiritual means.

Consider that “in Adam all die and yet all will be made alive in Christ” (1 Corinthians 15:22).

1. Original sin translated to death for all.
2. Salvation from death translated to being made alive.

Salvation and eternal life in Christ is the direct opposite of original sin and death in Adam. Salvation is passed to people spiritually, not by physical means and definitely not by genetic means. On this model, there is no reason to assume then that original sin was anything less than passed down by spiritual means; however, Romans 7:13–25 seems to locate the sinful tendencies as being part of the flesh (Greek sarx, meaning flesh or body). He states that nothing good dwells in his flesh (v. 18), that there was a law in his body warring against his mind (v. 23), and seeks deliverance from his [physical] body of death (v. 24).

It seems particularly difficult to explain this last view in completely laymen terms, because it is not based on any physical mechanism like the previous two. So let me say this: by virtue that we are sinners due to being descendants of Adam, we automatically receive sin nature not by any physical means, but spiritual means and Christ, being God, simply doesn’t receive it by virtue that He is the Son of God.

Conclusion: Mysteries belong to God

"The secret things belong to the LORD our God, but those things which are revealed belong to us and to our children forever, that we may do all the words of this law. (Deuteronomy 29:29)

In a discussion like this, it is good to keep in mind that there are many mysteries and secrets that belong to God. Even these explanations merely touch the surface and require years of research and books to cover this difficult topic. But the hope is that this short overview gives some food for thought.

But one lesson can be easily learned here: be wary of appealing solely to materialistic explanations in a world that is both spiritual and material.