Dad a cuckold too?

I am wondering if anyone else has a similar situation or experince. Maybe has some insight or suggestions.
First off I am 31 and have been married for 4 years this past March.
I have been cucked for almost 3 years though we had some threesomes and she had seen other guys before we got married. I really enjoy a lot of it though it can be hard still at times.
For the past 5 years or so I have slowly put together that my dad is a cuckold. Or at least I am pretty darn sure of it.
There is nothing concrete like actually catching mom with another man, just like many pieces of a puzzle. First there is just the way he acts around her. He will call me at random wierd late hours like 10 or so the past few years to say 'hi' and I can tell hes had a few and I ask where is mom and he says 'she had a meeting to go to' 'is out with friends' and things like that. If I ask what one its always something like church meeting (on a monday night?) or subdivision committee or the like or give me a vauge answer.
He never that I can recall initates lovey stuff with mom, she does. And I can say that mom definately rules the house, always has always will and has always been a stay at home mom, which has cool growing up. I can definately see the advantages it has for rasing kids now that I am getting older if you can afford it.
I remember many times as a young kid hearing a door downstairs close in the middle of the night. Id also hear footsepts coming up the stars but never go down or the opposite. There was also a few times that I would get woke up by a car starting what sounded right in the driveway a few times I recall going to the window and it was too late I would just see tailights down the road.
Dad would take us to the movies all the time on fridays or saturdays as a kid, sometimes to two back to back. Mom hardly ever went then and just didnt like to go to the movies much, but these days they go all the time together!
As a kid my parents bedroom was stricly off limits 24/7. they would even keep it locked. I did sneak in several times when I was older and had the house to myself to look around. Only thing intereting that I ever found besides the guns barried in the closet was the penthoues and playboys dad had in the nightstand on his side of the bed. Very interesting to a teen boy! Obviously mom didnt mind I guess, I cant se how she wouldnt know they were there. I cant belive she didnt know they were there and that many!
My parents didnt mind me staying out late when I was in HS, they were very insistant that I call no matter how late before I came home, even from a payphone and mom would always make sure before I left that I had quarters to call and would remind me all the time to call - they said for saftey, etc, and encouraged me to stay the nights at friends a lot. But it makes me wonder alot now.
Twice back then I came home without calling and there was a car parked out front on the curb where I usually parked. I remember one of the times I wanted to get something out of my room I forgot to take with me. I tried to sneak in the house since it was late very late and I didnt want to wake them, but the dead bolt was on from the inside so I couldnt get in.
The second time we had to leave where we were staying and I decided to go home. Same thing the deadbolt was on and I couldnt get in and there was the same car there. I never found out who's it was.
I went up to the closest grocery store where there was a payphone about a 10 minute drive (semi rural area) and called and told them I was coming home. When I got back the car was gone and the deadbolt wasnt on. I never mentioned this to them ever.
Our family has always been real big on christams cards, even to each other not juet extended friends and family. We always open them christmas morning. One christmas I accidentaly opened a christmas card that was in the stack for me but was actually for my dad. It didnt have a name on it and was in the stack for me so I assumed without thinking it was for me. I was from my mom to my dad on the inside and said something like 'I hope you are looking forward to your one time a year special night' I was an older teen so I knew exactly what that meant and I have never forgot it, that kind of thing sort of burns in your brain. It floored me.
Other things were when we were pre HS Dad would take me over my grandmothers (to his mothers) to stay the weekend. It was like twice a month. In itself innocent sounding, but now I wonder when I think about this....
So .....Lately all this has come up in my mind and I think about it alot. I have been like I really want to ask him if he is. Its like I got to know! Partially also because I sorta sympathize or something and I care and part of me just wants to know and I cant totally explain why. Im not sure how to bring it up and part of me doesnt want to in a way especially in case I am totally wrong.. But sometimes its like I just want to pick up the phone and straight up ask point blank sometimes or send him a text or something.
Im not sure I could do it face to face even though being forward and havig some guts about it might be the right thting to do. I dont know.
I go over all sorts of scenerios and thoughts about it alot now I wonder if he would lie? Id tell him it was totally ok and I have known for a long time and that I totally understand. I wonder if its something he wants to get off his chest or something, I dont know if I should tell him that I am too or save that for a later conversaion, or start out any approachment of the subject wth that and see how he reacts, or is that too much at once?
I wonder if It might make us more closer too, or would it or how he would react?
One the other hand it would also mean it would probably get back to my mom. That could get weird. I dunno maybe if I asked him not say anything to he wouldnt. I dont think I could go to my mom first about any of this first. It would be too much to tell her I think
And part of me says I should just not say anything or at least 'collect more evidence'
Sorry if I am rambling. Just a lot of things to put together. I am not the best writer in the world.
I dont even think I can talk about this with my wife and my thoughts before I confront him. Its like I would be violating his privacy or something telling it to her what I think is going on, and definately if it was true and I told her. Would that be right? At the same time we have always been very open wth each other. Its sorta a torn situation where I have let sitting dogs lay for a while.
I don't know if you could consider my father a cuckold or not, but I do know that promiscuity seems to run in my family.

Going way way back, my grandmother got pregnant and had a baby out of wedlock in 1913 when she was 19 and didn't marry the father. She married my grandfather in 1916 and had 3 more children, one of which was fathered by a hired hand. Her husband died in 1926 and 2 years later she again turned up pregnant, we believe by a neighbor.
Gram got around.

On to my mother: She had a baby out of wedlock in 1939 but married another man a few months later and had 2 more. Then WWII came along and her husband went over seas. While he was gone, she again got pregnant and her husband divorced her. She told my father it was his so he married her and they had 2 more. Turns out it wasn't his, it was his brothers.

I never discussed any of this with my parents and they are both gone now. I really wish I had.

My family tree has so many branches it looks like an entire forest