In the epistles of John, Cain is considered a son of the Wicked One. Also, Cain is not mentioned in Adam's genealogy (Genesis 5); therefore, is it possible that Satan seduced Eve (sexually) resulting in the birth of Cain? Please also take into consideration the tares of Matthew 13 spoken by Christ!
We will break your questions into two parts: Son of the Wicked One, and the Birth of Cain. Your last comment about the tares in Matthew does not apply to Cain. It deals with God’s Kingdom and the spread of the good news about Jesus Christ.
Son of the Wicked One
The epistles of John refer to Cain only one time. It is found in 1 John 3.
For this is the message which you have heard from the beginning, that we should love one another; not as Cain, who was of the evil one and slew his brother. And for what reason did he slay him? Because his deeds were evil, and his brother’s were righteous. (NASB) 1 John 3:11-12
Since the Bible was written in Greek it is important to know what the Greek actually says and not the English Bible one is reading. In this passage, the literal translation of the Greek reads as follows: “. . . Cain out of evil one was . . .” It is important to notice that there is no reference to Cain being a “son” of anyone. So the Apostle John did not tell us that Cain was born of the evil one.
Birth of Cain
The biblical genealogies do not record every son and daughter that were born into a family. So we should not be surprised that neither Cain or Abel were recorded in Genesis 5.
The answer to your second question is found in Genesis 4.
Now the man had relations with his wife Eve, and she conceived and gave birth to Cain, and she said, “I have gotten a manchild with the help of the LORD.” (NASB) Gen. 4:1
Cain’s father was Adam. Cain murdered his brother because he was just like the evil one. His character was “out of” the evil one. There is no man or woman who has not murdered someone in his or her heart. We are all out of the evil one in our hearts (see Matt. 5:21-22). Only God can change man’s heart and give him a clean one. It comes by trusting God. Learn more on the page “Searching For God.”