The narrative indicates “people” and a place called Nod where Cain finds a wife. A good detective would have issues with the story as presented.
Cain said to the Lord, “My punishment is more than I can bear. 14 Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth, and whoever finds me will kill me.”
15 But the Lord said to him, “Not so; anyone who kills Cain will suffer vengeance seven times over.” Then the Lord put a mark on Cain so that no one who found him would kill him. 16 So Cain went out from the Lord’s presence and lived in the land of Nod, east of Eden.”
So Cain bore the tribal mark of his mothers people. In that age people didn’t wonder around alone in the world with no tribal mark!
Well..... are you sure that's what it says?
Let's look at it:
Gen 4:14
הֵן֩ גֵּרַ֨שְׁתָּ אֹתִ֜י הַיּ֗וֹם מֵעַל֙ פְּנֵ֣י הָֽאֲדָמָ֔ה וּמִפָּנֶ֖יךָ אֶסָּתֵ֑ר וְהָיִ֜יתִי נָ֤ע וָנָד֙ בָּאָ֔רֶץ וְהָיָ֥ה כָל־מֹֽצְאִ֖י יַֽהַרְגֵֽנִי
The part to focus on is at the end. "
וְהָיָ֥ה כָל־מֹֽצְאִ֖י יַֽהַרְגֵֽנִי" It literally says "And it will be any find me will slay me". "
כָל" is any, not anyone, just plain any. Making it a little more readable, we can add a word "that". So the phrase is "... and it will be any [that] find me will slay me." That's it. A person isn't specificied. Cain is saying "any" not anyone.
Gen 4:15 It's basically the same thing as in the previous verse.
וַיֹּ֧אמֶר ל֣וֹ יְהֹוָ֗ה לָכֵן֙ כָּל־הֹרֵ֣ג קַ֔יִן שִׁבְעָתַ֖יִם יֻקָּ֑ם וַיָּ֨שֶׂם יְהֹוָ֤ה לְקַ֨יִן֙ א֔וֹת לְבִלְתִּ֥י הַכּֽוֹת־אֹת֖וֹ כָּל־מֹֽצְאֽוֹ
"
כָּל־הֹרֵ֣ג" - any [that] slay
"
כָּל־מֹֽצְאֽוֹ" - any [that] find him
Gen 4:16, Cain "knew" his wife and they conceived... It didn't say he found a wife. Cain could have brought a wife with him? We're not told that Adam and Eve had no other children. Yes it would have been incest, but that's not uncommon for primitive people. There is a legit theory, in my opinion, that Cain and Abel had twin sisters. Legit enough not to make assumptions. See below:
Aclima - Wikipedia.