I think my father french kissed me
Why would your father do that to you?
I just overheard him telling someone he french kissed me
It's wrong to engage in any kind of sexual behavior, such as French kissing, with a relative.  However, you would have known if your father had actually done this to you, so it's likely that he was just talking about something else.  Maybe he confused "French Kissing" for the kind of gentle kisses on the cheek that friends and family exchange in France.
Shit, it turns out he has been going around lying to everyone. He's been having a hard time and got some issues. Hope he gets better.
I am glad that you got a better understanding of your father's condition. Now you can help him through his troubled times.