The Sins of fathers visit upon their children ..

That is so true. They do say that the apple doesn't fall very far from the tree. Patterns tend to be repeated. If they are good, then wonderful things will happen. If bad habits and wrong family values are passed on, then it will be reflected in the next generation and so on.

its true if the parent is evil the child will learn from example!

Well, I have never looked at it that way before and hopefully that shouldn't be a problem at all. I don't think what your parents did should reflect on you at all.

It is not only the children of the person, but also all the family members of the person face the adverse results of the misdeeds of the person proportionately. Children, being the delicate ones, are more suspetile to the consequences. It is the law of Nature and it is desired by God to be responsible for practising rightousness by all for a better and virtuous life that is free from all sorts of misdeeds or sins. Better is the understanding as well as practising of rihtousness by all, better is also the social life. Exampls are many in history and mythology. Please study 'The Mahabharat' for a clear and greater example. Thanks.

This is true to a great extent, and observed in many cases, but is not a rule. I don't know whether it has got to do with the deeds of a soul in prior births, or what the reason is exactly, but many times in a family of corrupt father a son with good sense of values takes birth. Sometimes its right from the beginning and other times, over a period of time the child realises that he shouldn't be doing sinful things and turns to good deeds. You try to look around and you too may find such people.