Originally posted by Waxior:

breed? how? I got only 1 star2 at here island, if breed with normal boar+star2= still normal cub

A no-star boar will produce a no-star offspring.
A 1-star boar will produce a 1-star offspring.
A 2-star boar will produce a 2-star offspring.

You feed both boars, they both get "pregnant", they both produce offspring that match their own star level.

Once you have 2 boars that each have 2 stars, turn the others into boar jerky and make more 2-star boars. This isn't real life; "normal" physiology does not apply.