Their dad does not cuss in Russian.
This reminds me of a story...
I worked in peach packing houses before i was is enough to work elsewhere. You wore your old clothes to the job. This was in about the late-ish 1980s... who remembers Duck Head t-shirts?
So most of the guys on my line were Mexican. No habla English. There was one lady who spoke good English and Spanish.
One day she walks up to me laughing her ass off.... she starts by saying "you've got to promise not to get mad" and then says "all these guys know in English are cuss words"
Then she tells me one of the guys just asked her why my shirt said "Dick Head"...