One of the Greek words which Paul used to describe the Gentiles who had given up God was astorgos (Rom 1:13) The word is translated "unloving" in the New American Standard Bible but is translated "without natural affection" in the King James Version; in this case, the KJV is the more accurate translation.
Storge was the special Greek word for family love. Astorgos is a derivative of storge; it is prefixed with the privative "a" (compare "theist" and "atheist" to get the significance of the privative "a"). A person might be described as astorgos when he lacks the normal love toward his relatives.
Truth Magazine XIX: 8, p. 120