This week is an echo of sorts, as I realized part-way through.
(Chi wa arasoenai; “You can’t fight your blood”)
There’s no point trying to deny one’s heritage. “The apple doesn’t fall far from the tree,” as the Germans say. 蛙の子は蛙, perhaps. The wording might make this version sound darker, more fatalistic, more defiant to the Western ear, but apparently the phrase saw some use from servants and other low-status members of a household, to praise their young masters for mimicking the previous generation’s character, demeanor, or accomplishments.
血 (chi) is “blood,” used here in the same metaphorical manner as in the West, to indicate heredity. It’s marked by the topic particle は (wa), and followed by the verb 争う (arasou, with o and u standing as separate vowels rather than a single long o), “to contend,” in negative potential form – e.g. “cannot” form. The phrase, while brief, can function as a complete sentence. Stiffly translated, it would be rendered “As for blood, [you] can’t fight [against it].”
This kotowaza seems less well-known than the frog version. While I was looking it up, I found a number of pages where one Japanese person asked what it meant, and others responded by using 蛙の子は蛙 as a point of comparison.
(“Ha ha ha, omae, ki ni itta ze. Omae no oyaji mo, omae mo tantouchokunyuu da na. Sasuga, chi wa arasoenai!”)
[“Ha ha ha, I like you, kid. You get right to the point, you and your old man both. Like father, like son, for real!”]