hehe has the recorded history: An onomatopoeic representation of soft or sly laughter, formed by reduplication of the syllable he; imitative in origin. The history explains the modern form through the named earlier word or formation, without requiring a separate speculative ancestry. The etymology remains cautious where the history is cautious: comparisons, echoic formation, or disputed derivation do not make the ancestry more definite than the forms actually named. In present English, the interjection sense is "an informal written representation of soft or sly laughter", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as haha. Its semantic neighborhood includes haha, heehee, chuckle, and snicker, which helps locate the modern sense without adding a separate etymological claim.