i grew up in a cultured family from all over and everyone has their own way of doing something. I do have a cousin that does that, but its more to the side end of the mouth, its mostly affection and love of family. then i have some that do full on the mouth but its closed lips, i think its kinda weird, but ive grown accustomed to it. though its weird for alot of people to see, its become a custom now when i visit them, or they come visit us.
though it sounds more like he was kissing the side of her mouth and not full on the lips which would be gross, your sure if its a father & daughter? im not doubting you or anything ive seen some families do that, but it could have been an older man dating a younger woman?