Were there other people born to Adam and Eve who never sinned?

Were there other people born to Adam and Eve who never sinned?

No.

Adam and Eve had their first child, Cain, after being expelled from the Garden of Eden. The promise to Eve in Genesis 3:15 indicates that the Seed (offspring) of the woman was yet to come and give a mortal wound Satan, the serpent.

Genesis 3:15  I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel."

Eve named her firstborn son Cain whose name means "acquisition" saying "I have gotten a man with the help of the LORD."  Eve may have thought that she had just given birth to the Promised Seed that would lead to the downfall of Satan the redemption of mankind.  Cain was obviously not the chosen line of descent that would lead to the Messiah.  That honor would go to Seth, the third-born child.
Genesis 4:1-10 gives us the story of the birth of both Cain and Abel and the following argument between God and Cain about the nature of their sacrifices.  Cain brought a bloodless sacrifice from the fruit of the ground and was rejected.  Abel brought the lamb which was received, establishing for us the model of the shedding of blood for forgiveness (see Hebrews 11:4).

Although the details are not give for how long Adam and Eve were in the garden, Genesis 4:3 is the first time that the Bible mentions a significant passing of time.  

Genesis 4:3  In the course of time Cain brought to the LORD an offering of the fruit of the ground.
There must have been other children born to Eve, notably girls, but their names are not mentioned in the Scriptures.  Cain and Seth both took wives in marriage, presumably their sisters.

Shad Sluiter