"Disclaimer" While I did read some of the posts I did not take the time to read all of the other posts so I am sorry if I repeat someone else.
First look in Genesis, Gen 1:27 So God created man in his own image, in the image of God created he him; male and female created he them. Here it tells us that when God created us we were in His likeness and in His image, but now move on after the fall of man and read Gen 5:3 And Adam lived a hundred and thirty years, and begot a son in his own likeness, after his image; and called his name Seth:. Just by looking at these two verses alone we can see that there was a change from what we were to what we now are. and lest anyone should say that these verse are simply talking about physical likeness, they need only look in Eph 4:24 And that ye put on the new man, which after God is created in righteousness and true holiness. Two other verses I wan to mention before I move from Genesis. Gen 6:5 And GOD saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually. Gen 8:21 And the LORD smelled a sweet savor; and the LORD said in his heart, I will not again curse the ground any more for man's sake; for the imagination of man's heart is evil from his youth; neither will I again smite any more every thing living, as I have done. In both of these verses God sates that man is not good by nature but rather evil by nature.
Now look in Psalms 58:3 The wicked are estranged from the womb: they go astray as soon as they be born, speaking lies. Psa 51:5 Behold, I was shapen in iniquity; and in sin did my mother conceive me. Isa 48:8 Yea, thou heardest not; yea, thou knewest not; yea, from that time that thine ear was not opened: for I knew that thou wouldest deal very treacherously, and wast called a transgressor from the womb. All three of these verse say that from the very womb we are sinners, and lest someone should say that these verses only apply to certain individuals or certain groups of people compare them to Eph 2:3 Among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others. In this verse the all inclusive word "all" is used. Furthermore this verse goes so far as to say that we are by nature the children of wrath. Many more verses could have been cited but to save space I hope that these will suffice to give an answer to your question that YES there is a sin nature.
