Pretty complicated issues here. I read the entire thread and all I can say is that if you are apprehensive about asking your dad to smoke, then don't do it. If you go into it nervous or scared and he says yeah, things might get awkward once you are high. That's just me though. I'm more of an introspective smoker these days.
Let me share my "smoking with dad" story though. The summer before I turned 16 I worked and saved all summer to buy my own car when I turned 16. So, I walk out of the house to go to school one morning and my truck is gone. Thinking what the hell! So I go back inside and see a note my dad left that I missed saying his car wouldn't start and he needed to get to work so he took my truck, sorry. It was cool, obviously he needed to get to work and one of my good friends lived right across the street so I got a ride with him that day. So I come home from school that day and the phone is ringing. It was the old man. After a very brief conversation he says, "oh, btw, we need to talk about this STUFF I found in your asstray." Being 16 and having the typical mentality that nothing bad could ever happen, I left a few roaches in my ashtray. At think point I'm thinking I'm screwed, I'm never smoking again, how stupid could I be, and so on and so forth. Well he picks me up and as we are driving around I'm getting the lecture about how irresponsible that was, and how he could have gotten fired from work if someone happened to look inside and see it, or how he could have gotten arrested if he got pulled over, etc, etc. Then he comes off with, and I'll NEVER forget it, "you know, I don't care if you smoke, I did it when I was your age and still do sometime, but don't be that stupid to leave roaches in your ashtray in plain sight for any John Q. Law to see." Don't think I was ever that relieved in my life. I was thinking he was going to take my truck off me and who knows what else. That was the end of it.
Fast forward 2 years later. I had just turned 18 and we were up his friend camp for the opening day of trout season. Since I was about 15 or 16, I had always been allowed to have a few beers up the camp as long as mom didn't find out. Even at 18, I knew the truth about marijuana. It wasn't evil and for the most part was harmless. Back then, and still now, I feel alcohol is by far more dangerous of a drug. So I figured, if we drink together, why can't we smoke together? I was a little hesitant. I've calmed down a lot since then but I guess I'm still what you would call slightly high strung. Well, he beat me to it. He told me to come out back to see the new deck he and his friend put on the cabin a few weeks prior. That's when he pulled out a little one hitter made out of plumbing fittings. We each had a few puffs and started talking about weed in general. How much I pay, how good the stuff is around these day, how much he paid back in the day, etc. Typical old head/young guy weed talk. The conversation kind of just died and it started to get awkward so we went back in. That was over 10 years ago and we haven't smoked together since. It was just too awkward for me. Think when he saw how uncomfortable I was that made him feel weird too. We've talked about it a few times, but he says he doesn't smoke anymore, which I sort of believe.
At any rate, the choice is yours and yours alone. Like I said, if you are hesitant to do it, then I wouldn't. Almost like taking mushrooms or LSD. If you go into it thinking you are going to have a bad time then there's a good chance you will. If you think you are going to have a great time thn you probably will.