Does the actions of one's ancestors pass down? I want to know whether the action of ancestors will be pass down to their children in the form of karma?.. 
A father's decision can affect his children like father quitting his job and staying at home can affect his children...but What i want to know is, if someone has a very crual father does atleast some of his bad karma gets pass down to his later generations not just to his childrens but maybe to great grand children...like for example a person's great grand father may have killed someone...and due to that this person is having a major disease...
Does karma works in this way?
People, beings find together of cause their inclinations. Relations usually as well. And grandchilden are often rebirth of their anchestors as well. Don't one forgeth that as well. So it would be not correct to say that there is no connection as there is a long time feed each other behind. So take care with whom you chose to associate. At least the smell will be on you.

That goes also toward your own behavior. Others, with similar origin may suffer from your possible behavior or benefit from your reputation according to their individual kamma in addition. There are no such as innocent phenomenas, people, as well as there are no "guilty" ones. Causes have effects and they lead all back to ones past and present deeds on touch.

But the fact that people, beings, are after the same food, certain conditions, does not mean that they act always equal. What ever one does identify oneself with it, is sooner or later suffering. So that's the reason why best possible relations are seeked to go beyond relations. It's not possible to say that you are lucky or in big misfortune to ever asked here, whether you get touched physical, or mental, right or wrong for your best, who could decide for you where to put attention on? Who could prepare your required foundation to receive what gives liberation?

See also Why beings take birth, even in most worse existences and circumstances?

So it's good to think on: Darkness here as well. "May all beings make the right choices to gain happiness for themselves with ease", is a good thought to leave it.

(Note that this is not given to leave one in trade, exchange, stacks bond, but as a tiny door for an exit.)