Genesis 4:7

Hebrew Ambiguities

toward you is his longing, and yourself/herself is reigning in-himself. The ambiguity of the verse is such that it is quite enigmatic. This apparently led to a lot of violation of basic Hebrew grammar, with the intent to force certain meanings upon it.

Strong's H4910 - משל (mashal):
Verb root meaning to rule, dominate, reign

The Hebrew אתה otah can be either yourself or herself, see Genesis 6:14, 16:3, etc.

The Hebrew verb תמשל (timšol), from the root משל (māšal, Strong’s #4911 or #4910), is morphologically ambiguous in the Qal imperfect, potentially conveying either “you (masculine singular) will reign” (2ms) or “she will reign” (3fs). This form arises from the common prefix ת־ used in both grammatical persons and is disambiguated only by context. In Genesis 4:7, the accompanying pronoun אתה (“you [masc. sg.]/ her [fem. sing]”) is also ambiguous as the subject.

The King of (within) Kings

Take note of 2 Chronicles 9:26 using this verb, speaking of Solomon:

ויהי מושל בכל המלכים

"And he is him who reigns as king within all the Kings" 

Because the noun חטאת (“sin/missing of the mark”) is feminine, and תשוקתו cannot refer to the sin because the possessive is masculine, "his desire," a different reading proposes that the sin/miss is the subject: “she [i.e., sin] will reign in you,” inverting the received sense of the passage which has traditionally mangled or ignored the grammatical rules.