Through thick and thin we will survive but he gets only one shot at it!
Infidelity in my husband's family - zero. His dad was a faithful husband for 55 years - they died within 3 months of each other. WH has 3 siblings and to my knowledge all of them are faithful spouses.
Our kids know already - home life has been rocky! They are aware that WH has screwed up in a big way. But given that he had several affairs and one was a LTA I often wonder if that may be a "risk" factor for my sons.
My reasons are different, because my H did not come from an infidelity environment, but I did and he knew the pain it caused me (my bio dad cheated on my mom and all his other wives as well) and we discussed it openly and it made no difference in what he did just added guilt and a deeper desire to HIDE is all.
I want my kids to know because I want them to realize it can happen to them, they could be "torn asunder" by the one who promises to be faithful to them one day. I want them to be able to take care of themselves irregardless of their mates actions and to build a life they take comfort and pride in whether or not they have someone honorable enough to share it with them or if they have to go it alone.
With upwards of 50% of people cheating anyway, I am not sure I buy any familial component. It is more likely poor coping/intimacy skills, which are largely learned, not genetic.
Which is all the more reason I think, to share that with grown children. My H and I agreed we would someday tell our children who were already grown at the time of the infidelity. My daughter was already married and both my sons married within 2-3 yrs after dday. We still weren't ready then, before they got married and I'm ashamed to say we still haven't done so. And by we, I mean him.
I know several books point out that if you have infidelity in your family, you are more likely to do so. My husband's father had an affair for 10 years before he left for the OW. It devastated my husband when he was 12 years old. Yet he walked the same path. His IC has some interesting theories as to why. We both thought his anger at his dad was an inoculation against cheating. Turns out, notsomuch.
Our kids have a general idea, but we will tell them more when they get older.
That said, I DO believe they should know someday. But when is someday? 18? 19? 21? Before marriage?
My parents have been married for 41 yrs, his have been married for 52 yrs. No cheating on either side. But for some reason his parents seem to think that it is ok that he cheated, I guess because I am such a bitch...