It should mean something like "If the ancestors are cruel, so would their offsprings" right?
Hm, if you're asking about English, wouldn't the English language SE be more appropriate?
「酷い」 here does not mean "cruel", but more like "terrible" or "awful".
The closest English equivalent I can think of would be:
Like father, like son.
Though note that the English can have either a good meaning or a bad meaning, unlike the phrase you posted.
That aside, the phrase you have posted is rather uncommon. The idiom used in Japanese is:
Note that this phrase is used in a negative way only.