Lust: personally I believe that Jesus flesh (sarx) had all the appetites of our flesh.
These appetites in and of themselves are not sin: desire for food, drink, comfort, a mate, a family... etc.
Jesus had them, He hungered, was thirsty, etc...
Where sin enters in is when we satisfy these desires apart from the known will of God (in Jesus case, under the Law).
He never gave in to them, not even in the Garden where He agonized at the thought of the cross, He sweat blood as a result of the conflict (for lack of a better word).
Luke 22:42 Saying, Father, if thou be willing, remove this cup from me: nevertheless not my will, but thine, be done.
Personally, I don't care whether it was "He would not" or "He could not" sin, I love Him because He first loved me and went to the cross for me.
Sin nature:
Romans 8
21 Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God.
22 For we know that the whole creation groaneth and travaileth in pain together until now.
I believe the entire material universe came into the state of corruption because of Adam's sin and is far wider in scope than the just the human race, down to the atomic and sub-atomic particles.
Entropy, the energy death of the universe, the entire universe is caught up and in bondage to the result of sin and death.
The Y chromosome thing is just a small part of the entire impact.
sarx - "flesh" has both a physical and metaphysical component which may or may not impact the human genome and its DNA/RNA as related to the sin nature. Personally I believe it does.
But why trouble ourselves with the details we probably couldn't understand anyway in our present state?
When I heard His call and came to Him, none of these things and questions were there, yet I was freed from sin and death.
Matthew 11
28 Come unto me, all ye that labour and are heavy laden, and I will give you rest.
29 Take my yoke upon you, and learn of me; for I am meek and lowly in heart: and ye shall find rest unto your souls.
30 For my yoke is easy, and my burden is light.
John 5:24 Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.
Revelation 21:6 And he said unto me, It is done. I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely.
Revelation 22:17 And the Spirit and the bride say, Come. And let him that heareth say, Come. And let him that is athirst come. And whosoever will, let him take the water of life freely.
Yes, it's good to talk about these "hard to understand" things, we could do worse, but when we don't understand here is what we need:
Proverbs 3
5 Trust in the LORD with all thine heart; and lean not unto thine own understanding.
6 In all thy ways acknowledge him, and he shall direct thy paths.
7 Be not wise in thine own eyes: fear the LORD, and depart from evil.
Proverbs 18
10 The name of the LORD is a strong tower: the righteous runneth into it, and is safe.
HankD