I have parents who clearly are only together out of comfort and loyalty, and to look after a disabled sibling. They get on for the most part, but their differences are quite obvious and I don't think they'd be together it it wasn't for my brother.
Their relationship has probably been that way since I was a kid and I never outwardly noticed the issues or lack of romantic love between them (and I had an awesome childhood- they are amazing people). But as an adult now my intuition, particularly as I got older probably did pick up on it subconsciously, and I would say that that the family dynamic isn't 'traditional'.
I am overall a well rounded individual, with a loving family BUT I think its certainly has impacted my view of relationships, myself and life even in subtle ways.
I've recently split from a long term ex whom I hadn't been happy with for some time, with the view that 'I must make it work, because that's what you do'. I probably would have stayed with him regardless of how miserable, tired or low it made me, because that's what I've seen others do and you always put your other half first and not yourself. I also probably lack quite a lot of confidence to speak up for myself and to actually put my opinion across in certain situations ( funnily enough not to my family, but particularly in relationships). I partly think that's because of the fact my parents 'just got on with it', and so I've learnt to as well. I certainly don't consider my feelings first, and I carry a lot of guilt that I have it easy and my sibling doesn't etc etc. I could launch into lots of subtle ways it's had an impact, but I won't!
I am sure there are platonic marriages which are perhaps slightly more 'traditional' than my families set up and are completely happy and settled with that (and therefore have no impact on children), but in my case there has been an impact on me especially in adult life, however not saying it would be the same for everyone though. I am currently trying to unpick some of it through counselling after my relationship break up, because it isn't healthy behaviour.